Why didn't any parents complain about what was going on at Hogwarts?

Question

In regular schools parents will come to meet the principal or other leadership if something bad happens. The same should apply to Hogwarts, but it doesn't seem any parents complain. We only see Lucius Malfoy trying to kick Dumbledore or Hagrid out of office. There's plenty to complain about:

1. Gilderoy Lockhart
2. The Basilisk
3. Dementors (third book)
4. Umbridge

The list goes on.

Most of the children obviously suffered from the above and would have written about it to their parents. Maybe we don't see any parents complaining because the story is set in Harry's perspective; BUT a complaint about, say, Umbridge would have surely made headlines?

Why don't the parents take an active roles in their students' lives by complaining?

Answer 1

They do complain

"Really, Hagrid, if you are holding out for universal popularity, I'm afraid you will be in this cabin for a very long time," said Dumbledore, now peering sternly over his half-moon spectacles. "Not a week has passed since I became headmaster of this school when I haven't had at least one owl complaining about the way I run it. But what should I do? Barricade myself in my study and refuse to talk to anybody?"
_{Harry Potter and the Goblet of Fire, Chapter Twenty-Four - Rita Skeeter's Scoop}

There are also instances of parents visiting the school and taking their children out of school. Dumbledore's dealings with parents aren't shown (much) in the books because we're generally only exposed to what Harry experiences, and there's no reason he would be part of those interactions.

Answer 2

Parents do indeed complain to Hogwarts.

Parents do complain to Hogwarts about particular issues they wish to see them address. In fact, Lupin resigned when it was mentioned over breakfast that he was a werewolf partly because parents would start sending owls to Hogwarts complaining that a werewolf was allowed to be teaching there.

“I think the loss of the Order of Merlin hit him hard. So he – er – accidentally let slip that I am a werewolf this morning at breakfast.’

‘You’re not leaving just because of that!’ said Harry. Lupin smiled wryly.

‘This time tomorrow, the owls will start arriving from parents – they will not want a werewolf teaching their children, Harry.”
_{^{- Harry Potter and the Prisoner of Azkaban, Chapter 22 (Owl Post Again)}}

Additionally, parents also complain to Hogwarts about matters less dramatic in nature than whether werewolves should be allowed to teach, such as the content of the Hogwarts library.

“More than one parent has demanded the removal of this particular tale from the Hogwarts library, including, by coincidence, a descendant of Brutus Malfoy and one-time member of the Hogwarts Board of Governors, Mr. Lucius Malfoy. Mr. Malfoy submitted his demand for a ban on the story in writing:

Any work of fiction or nonfiction that depicts interbreeding between wizards and Muggles should be banned from the bookshelves of Hogwarts. I do not wish my son to be influenced into sullying the purity of his bloodline by reading stories that promote wizard—Muggle marriage.”
_{^{- The Tales of Beedle the Bard}}

So yes, parents do complain to Hogwarts about various matters, both small and large in scale.

But parents are not always told of events.

However, parents can only complain to Hogwarts about events if they are aware of them, and parents are not always made aware of certain events at Hogwarts. For example, the official story told by the Ministry claimed Cedric’s death was an accident.

“They stared avidly from Harry to Professor Umbridge, who had raised her eyes and was staring at him without a trace of a fake smile on her face.

‘Cedric Diggory’s death was a tragic accident,’ she said coldly.”
_{^{- Harry Potter and the Order of the Phoenix, Chapter 12 (Professor Umbridge)}}

Myrtle’s death also was most likely explained as an accident - Riddle says from his diary that the story given out was that the death was a freak accident. While Riddle is untrustworthy, since giving obviously false information if his claim is verifiable could expose him as lying, he is likely telling the truth about the official story.

“But the Headmaster, Professor Dippet, ashamed that such a thing had happened at Hogwarts, forbade me to tell the truth. A story was given out that the girl had died in a freak accident.”
_{^{- Harry Potter and the Chamber of Secrets, Chapter 13 (The Very Secret Diary)}}

In addition to the Ministry and Hogwarts not always telling parents the truth, their children may not tell them what is going on either, particularly if their parents are Muggles and have little connection to the wizarding world.

“My parents are Muggles, mate,’ said Dean, shrugging. ‘They don’t know nothing about no deaths at Hogwarts, because I’m not stupid enough to tell them.”
_{^{- Harry Potter and the Order of the Phoenix, Chapter 11 (The Sorting Hat’s New Song)}}

Parents do not complain about certain events more because they are unaware of them, and therefore unable to complain.

Answer 3

What, exactly, would their complaints do?

The already-posted answers do a great job of pointing out that parents do complain, and apparently frequently, even if it's not explicitly shown much.

But another factor to consider is: what would be the goal of the complaints? It doesn't seem that most parents have any real ability to influence Hogwarts at all, save for possibly removing their children from it. There isn't really a public body to which the parents can complain (like a political office to lobby to install a new superintendent or principal), or any known processes for their complaints to be addressed.

So their only real influence is to remove their children from the situation, which they do at times (particularly in Chamber of Secrets, as I recall).

Oversight comes from a relatively small group of people (the board of governers, I think? I'm away from my copy at the moment) who have the authority to do more than complain aimlessly. But in the time covered by the books, that group is dominated by Lucius Malfoy. He was on board for most (if not all) of the things on your list, and his feelings towards the school seem often to be overshadowed by his goals elsewhere (for example, Umbridge was nominally anti-Voldemort while a professor, but her presence abetted his return to prominence nicely enough).

Wizarding life is more exciting than mundane life

Witches and wizards also deal with more substantial dangers in their everyday lives which are well beyond muggle experience (a muggle is not going to splinch themselves), and they also have vastly superior methods for dealing with many of those dangers (even if a young witch or wizard splinches themselves, the damage can be completely repaired in moments).

These almost certainly skew the perception of danger in ways that would not resemble the perceptions of muggles reading the stories.

Many of the problems simply don't last very long

Most of the problems end up solved, or otherwise dealt with, relatively quickly. Bad teachers rarely lasted through an entire school year, the dementors were a response to an immediate (perceived) emergency, the basilisk was killed, and so on.

Parents could complain about specific things, but generic complaints about living in a magical and dangerous world are probably not going to accomplish much.