Warning: Rant Following
I hate late people. I hate them. It is so inconsiderate and disrespectful to be late. I think late guidelines should be instilled into our collective etiquette. Up to five minutes is allowed, then I require excuses. Five to ten minutes and the culprit can get by with a token excuse. (Think "the elevator took forever!" sort of excuses.) Ten to fifteen needs a GOOD excuse. (Think "I was on the phone with my mother.") After fifteen, I'm walking. Harsh? Hell no. Time is money, people! And I hate to waste money.
Edit: Yes, I agree that there is such a thing as "fashionably late," but I think that only applies to parties, at which time a half hour -- even an hour -- is A-okay. When we're talking about situations with reservations involved, you should not arrive at the meeting point -- and I'm NOT talking about the ultimate destination -- at the time of the reservations themselves.