Most people just don't follow the basic ettiquette rules now a days. Who writes thank you notes now??? I still do. I went to a wedding once and the bride e-mailed me a thanks!

I couldn't believe it. (gee, hope no one here has done that.... foot in mouth

) I don't know if parents aren't teaching them or if people are too lazy to put a reply in the mail or what. It can be VERY frustrating.
Wouldn't it be fun to have a RSVP party and then when people show up that didn't RSVP, tell them - Sorry, but we weren't expecting you, and turn them away.

I would never do it, but my twisted mind thinks of things like that.