Chicago's Doug Simmons and Dedra McGee were not happy when some of their wedding guests didn't show up to the ceremony, even after RSVP-ing. So, naturally, they sent the no-shows an invoice to cover the cost of their attendance: $120 per person.
Is it tacky? Sure.
Is it understandable? Absolutely.
Weddings are expensive af. When someone invites you, that means they're willing to pay exorbitant prices just for the benefit of your company on their special day. To RSVP and then not show up without any notice whatsoever is incredibly disrespectful. People save up for YEARS for these (I'm saving up right now and expect to reach our desired value in about 10 years lololol), typically spend a year planning every single little detail, and then to just get stood up? I get it.