I have never really thought about wedding etiquette. I get an invite, I show up, give a gift, enjoy the night, go home. I very recently became engaged and started frequenting forums and was really surprised by some of the faux pas.
For example, where I live, open bars are a bonus, a big bonus. In fact, I have only ever been to one wedding with an open bar. And I have been to a lot of weddings. I have never been to a dry wedding. Here, reception = cash bar. Since I learned this, I have asked a number of people my age, all who have never heard of this idea that a cash bar is rude (haven't had a chance to ask my mom).
The other glaring one - tiered receptions. Just yesterday, i was reading a thread on tiered receptions. Also yesterday, I had a discussion with a co-worker about her exploding guest list. Her solution was to order reception cards, inviting people to the wedding and reception, not the supper. I never would have thought twice about that. It had never occured to me it was rude. I just always thought the reception is the fun part, and it is expensive to feed everyone so I was ok skipping the dinner (typically the dinner would be over and cleaned up before the time of the start of the reception on the other invite) I have been invited to the wedding/reception only before. I came home and asked FI about it, he also said it was pretty common and accepted.
Now, after reading here, I get why they are considered rude. I had just never thought of it that way. I am not arguing they aren't. I was just kind of surprised since these are very common where I am and generally accepted. Am I the only one where these things are common?
*edited to correct spelling*

The Twins