We know that Harry receives a present for Christmas from the Dursleys even while he is at Hogwarts. Here are the quotes I remember:
A second, very small parcel contained a note.
We received your message and enclose your Christmas present. From Uncle Vernon and Aunt Petunia. Taped to the note was a fifty-pence piece.
Harry Potter and the Philosopher's Stone Chapter 12: The Mirror of Erised
She nibbled his ear in an affectionate sort of way, which was a far better present than the one that she had brought him, which turned out to be from the Dursleys. They had sent Harry a toothpick and a note telling him to find out whether he’d be able to stay at Hogwarts for the summer vacation, too.
Harry Potter and the Chamber of Secrets, Chapter 12: The Polyjuice Potion
Harry’s other presents were much more satisfactory than Dobby’s odd socks — with the obvious exception of the Dursleys’, which consisted of a single tissue, an all-time low...
Harry Potter and the Goblet of Fire Chapter 23: The Yule Ball
We see that in Philosopher's Stone, their present is part of a reply to a message Harry sent them, presumably to tell them he'd be staying at Hogwarts for the Christmas holidays.
We also see that in Chamber of Secrets, Hedwig brought Harry their present. But how did Hedwig know the Dursleys would want to send Harry a present? The Dursleys had no means of summoning Hedwig. If she was smart enough to figure out it was Christmas and Harry should receive a present from them, she might be smart enough to figure out the Dursleys hated Harry and they wouldn't send Harry a present (I don't think toothpicks, tissues,etc. can be termed as presents).
In Goblet of Fire, there is no mention of how the Dursleys sent their present. Its obvious the Dursleys would rather eat their television than search for a wizarding post office just to owl Harry his present. Assuming it was Hedwig again, how did she know and why would she make the trip?
My question is: