I think they tried to make it as classy as they could.
As for the food though, I saw pictures, and it looked like it was Costco food. His mom made the cake and his brother (who is a chef) made a fancy watermelon...
Oh the horror! Costco food!
Seriously, why on earth do you care about this? It's icky that you feel the need to put these people down. Yes, there is a tacky way and a nice way to do everything, but where you buy your food has nothing to do with it. I really respect people who set a budget and stick to it for their wedding.
That said, FB invites to 500 people is the only icky thing I see here other than the OP's weird judge-y-ness. Etiquette is about making others feel comfortable and included, and nothing says you are not special to us like knowing the only trouble the bride went to was pressing "send to all". In this case, if I were the bride, I'd compile a list of however many I actually had room to host (even if it was just for "costco food"), and then call each guest with a personal invitation. I would make each call myself and not let MIL or my own mother help.
But clearly, doing-unto-others does not run in this family.