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.
I definitely think this is true socially. The ability to text at the last minute makes for a very different situation from when we couldn't get in touch if we were (unavoidably) unable to stick to arrangements and knew that the person we were meeting would be hanging about until they gave up and went home.
I don't like last minute cancellations, as they take no account of the fact that people spend time getting ready, may have organised other commitments around the meeting and so on. I used to meet a friend for lunch and would skip breakfast on the day of our meeting, but she would often cancel half an hour before, so I was hungry and had nothing prepared as I thought I was eating out. Sometimes I had no plans for dinner either, as I was expecting to have had a big meal at lunchtime. Infuriating. I stopped the arrangement in the end as it happened so often.
When it comes to tradespeople there is no excuse either. It gives such a bad impression when they can't turn up on time, or even message to say they will be late. I appreciate that a plumber can't leave a customer with a gushing leak in order to price up a job elsewhere, but it takes 30 seconds to ring or text to say they will be late, and there is no excuse for not turning up at all.