When my DH and I married, we got a HUGE range of gifts - some cheaper, some more expensive... One in particular that stands out was a gift bag filled with all of the non-perishable items required to make the gift-giver's favorite chili recipe (included on a hand-written card), along with a few boxes of cornbread mix, and an oven mitt and kitchen towels. The most expensive gift we received? No. The most useful? Not really, because my husband hates even the smell of chili, so I can't make it when he's home. Was it very sweet and thoughtful and much appreciated? Absolutely.
A wedding is about a marriage, first and foremost. Guests should only be invited because they are important to the bride and groom or their families. Because guests are invited for their company and their witness of such an important event, gifts should be considered secondary. I also had people who showed up for my wedding who didn't bring even a card. I'm not offended in the least - a little curious on some, I admit, but not offended, and I certainly would never even bring it up, much less berate them for a total lack of gift. I find it befuddling that anyone would be so crass as to embarrass or hurt people who were important enough to be invited to a wedding because of (a lack of) money spent.
I don't think this is a matter of culture, I think it's a matter of class.