I'm from Chicago area and used to the big Italian weddings with multi-course sit-down meals and a huge dessert table/room after the cake. I had never been to a wedding (even buffets) that did not have assigned seating until....
A few years ago my mom and I flew to Dallas for a wedding of one of her cousin's daughters. There were only a few of us representing the father of the bride's family as most of us are in Chicago. Most of them took the shuttle from the hotel so they didn't have to drive.
Well... after the beautiful, elaborate church ceremony, we all went to the banquet hall - which was a building in the middle of an industrial complex that housed just two banquet rooms (with a small prep kitchen) and bathrooms. When we arrived, we noticed it wasn't assigned seating - except one table said "reserved for father of the bride family" - which we assumed (correctly) was us and we sat down.
The bridal party arrived and they launched right into a dance party. There was a beautiful head table, but I never saw anyone from the bridal party sit down. The DJ started playing dance music, and they made an announcement that the buffet was open and special drinks available at the bars.
So we got our food, sat down and ate... and 20 minutes later we were all sitting there wondering what to do? We're used to long speeches by everyone and their brother so that at least a hour or two pass before we even get our food. Here we are, 30 minutes in, and we're done eating.
It was obvious that there weren't going to be any formalities, so we went to get cake - which was cupcakes. Some of my family was too afraid to get a cupcake without being invited, but we took a few from the back of the display anyway. Of course my mom and uncle need coffee with cake... no coffee! It was never ordered with the catering package. My mom and uncle tried sneaking into the other banquet room for coffee, but opted not to.
I danced for a little while, but felt bad for my relatives (ages 60+) who had flown in for the wedding and were essentially trapped there. At 8pm they were done eating and dessert, only loud dance music, and the shuttle wasn't picking anyone up until 10pm.
Don't get me wrong, I'm not judging my cousins' choices for her wedding. It was just unfortunate that guests weren't given a good expectation of the differences from what we're used to.
We're also used to just giving money in a card, for years I never saw anyone actually bring a wrapped gift to a wedding. Until college when I went to a wedding in Wisconsin, where they not only gave wrapped gifts, but they stopped the dancing for an hour and went on the dance floor to open them all. The bride told me later she thought it was odd I gave her a card with cash - she thought I was being lazy - and I thought it was odd when she was surprised that I hadn't planned time during my reception to open gifts (of which she gave me a lovely homemade item).
I think we all come in to weddings (and other events/experiences) with expectations based on what we know. I've now learned to expect anything and go with the flow. If that's what the bride and groom chose, then I support their decisions - it's their day, not mine.