> When I throw parties in the US nobody shows up until 30 mins after the start time But if you expect people to show up 30 mins. late structurally, why not jus

> When I throw parties in the US nobody shows up until 30 mins after the start time But if you expect people to show up 30 mins. late structurally, why not just give a time 30 minutes later and have them be on time ? All this does is cause unnecessary ambiguity.