I don't know about rest of the world π, but it seems like turning up late is almost a norm here in my country.
I was invited to an anniversary party. The timing was for 7pm. I called up my friends to plan if we can go together. I asked what time everyone wants to go? 6:30-7? And one of them says - "School thodi ja rahe hai jo time pe Jana hai? 9 bje jayenge" (Translation: Are we going to school that we need to report on time? We'll go at 9)
I understand why it's almost expected here. Most wedding/other parties have a LOT of guests 200-300 or even more. So people usually go only for the food. Go have snacks. Have your dinner. Catch up with some old friends of you find them in the sea of invitees π. Get back home. Also the girls take a lot of time getting ready - parlour duty π. Even the bride is usually late to her marriage.
How is it in your country?