Tree guys, carpenters, builders, painters, plumbers are ALL jammed up with more work than they know how to handle, and that is a bigger problem today than ever before. Most of the guys working the trades, most, NOT all, are not highly skilled when it comes to being organized. They're also pretty lousy communicators.
And the good tree guys this time of year are booked out weeks, if not months ahead.
Try being in the HVAC business on the first 90 degree day of summer, and first sub 30 degree day in winter, added those hot summer and cold winter months after those "first" days LOL
This is why customers tend to complain about pricing on HVAC companies when their buddy who does side work out of his house says they're being charged too much.
Most people who are good at a trade can not only be a horrible communicator, but also a can be a horrible businessman. Ask a contractor what his cost of doing business is in a percentage vs sales and he'll give you a blank stare.
All that said, a good business principal is to ALWAYS get back to a potential customer quickly, even if you can't do the work. That's just common courtesey which reflects on your business principals IMO.
I had to have the shingles replaced on my roof a couple of years after we bought our house. I called 6 contractors (in December) because the first 3 wouldn't pick up the phone. The contractor who did the job was from the county over, and he originally wasn't going to come out to quote the job because (after talking with him and asking him why) he said my county was nortorious to his business that he was always too high and that the homeowners would just get their relatives to help them out to do the work. I asked him if he was licensed and insured, which he said he was, and I asked him how long he's been in business, which was over 12 years. I told him to come out and price it, and assured him I didn't have any relatives living in the county LOL. He gave me what both my wife and I thought was a reasonable price for what we wanted, and he even came out the day before Christmas to do the job (I remember that day, beautiful for doing work outside, mid 60's and not a cloud in the sky). Thing is, in March I actually had a contractor finally call me back asking me if he still wanted to quote me on the roof.
Do remember one tree guy who started the job on trees, and he told me he'd have everything done by Friday (2 day job), and Friday rolls around and I get home from work at the end of the day and the job isn't finished yet, the guy left, but the guy calls me and wants to be paid in full. Told him that's not how I operate. I did pay the tree stump grinder guy the guy "sub'ed out" to finish the stumps the following week. Talking with the tree stump guy, he confirmed my suspicions that I should never hire this same "tree guy" again.
And I happen to agree with the OP as it has happened to me in the past before. You set an appointment, and no one shows up and never even calls you AFTER the appointment. Kind of like your appointment never existed.
I have an appointment with a customer at 0900, and if I see I'm running a little late, I'll ALWAYS call or text and let them know what time I should be there and apologize for being late. Just common courtesy.
All that said, there are some very interesting homeowners out there that I do believe have some unrealistic expectations. I don't believe I'm one of them though.