I believe that showing up on time for appointments (as a client) and providers being ready on time is a matter of basic decency. As @ButchAtlsays, “things happen” and if some sort of life event happens, I understand.
I had an appointment recently. Travelled a distance to get to the masseur. It was a first visit. I’m near him and texted 15 min before the appointment asking for exact address and apt/room number. At 5 min before our appointment, he texts me, “Shit. Can we do this an hour later?”. I message back with something like, “I’m on the street and don’t really have anything to do for an hour. Any chance you can be ready in < 1 hour?”. 20 minutes goes by before I get a reply. And, through the text convo, never an “I’m sorry” or any sign of regret for disrespecting my time. I think that’s what bothered me the most.
I ended up cancelling. It just didn’t feel right.