Mr. Weasley studies muggles, yet struggles to understand their non-magical items. Hagrid is ignorant regarding soccer. When the need arises they are quick to adjust muggle memories when the muggles have seen something magical. They walk amongst, live near (& sometimes with) muggles, and share train stations and roads with them. Last, but not least, the Wizarding world is full of muggle born Wizards. How is it that the Wizarding world is so uneducated in the ways of muggles?
Due to the Statute of Secrecy, most Wizarding families don't hob-nob with Muggles. While some Wizarding villages, like Ottery St. Catchpole and Budleigh Babberton, are home to a mix of wizards and Muggles, the Muggles are often unaware that their neighbor is a wizard. Sometimes, as in the case of 11 or 13 Grimmauld Place, the Muggles may not even know they have a neighbor, as for all any other resident of the Place knows, Number 12 doesn't exist.
Now, the Statute has some exceptions; there are some points of contact between the Ministry of Magic and Muggle government, primarily the Prime Minister. In addition, wizards and witches are free to marry Muggles (Seamus Finnigan's father is a Muggle, who didn't know he was marrying a witch until after tying the knot), and new wizards are born to Muggle parents all the time, who then have to keep the secret (it's kind of impractical to have to keep Obliviating Muggle parents' memories). In addition, we know Squibs exist, and they are usually encouraged to integrate fully into Muggle society. The Weasleys, for instance, have a distant relative who was either a Squib or decided not to pursue a magical education, in any case becoming an accountant. In these situations, the line is blurred, and people involved get a pretty good grounding in both cultures.
But, if you're born to two wizarding parents, with jobs in the wizarding world, you generally have a completely different way of doing almost anything. Transportation, communication, medicine, even cooking and cleaning are completely different, with very little overlap (the series does have a few bewitched cars with some nice tricks, like a sedan seating a dozen people and their luggage comfortably). If you grew up thinking that standing in your chimney, announcing where you were going and throwing a handful of dust at your feet was a perfectly normal way to travel, then getting somewhere via the Underground would seem odd.
I think a large part of it is just not caring. The wizards view themselves as living in a different, better world so the weird things Muggles find themselves interested in or amuse themselves with just doesn't seem of interest.
I also suspect a lot of wizards, even when living in a mixed Muggles/magic town or village, would have to keep to themselves, or at least to Wizarding folk. A lot wouldn't be able to invite Muggles over because of self-cleaning brooms, or clocks that let the family know who's where, etc. With instantaneous transportation via Apparation and Flue powder, you could always spend whatever time you want with your magical friends anyway.