Nellietheelephant
This may be part of the lifestyle of "the young" nowadays. My daughter (40something!) constantly makes arrangements to meet up with her friends and one or the other of them nearly always texts to say they will be late. No-one seems to mind or take offence. I suppose the ease of modern communication is the reason, really.
Ease of communication is definitely part of the problem. As a teenager I used to make arrangements with friends at school and if things changed I couldn't let them know as we didn't have a house phone and it was long before mobiles, so I couldn't change plans or I'd have had no friends. I used to say that to my DD when she was calling a friend to say she was running late... - a common occurrence. I was never let down either back then.
Last week someone came for an appointment and was one minute late, but apologised! Mind you I'd been let down the previous week by his colleague who's car had broken down, but he did let me know.