As an independent auto garage owner, not for any bikes but my own, I understand your frustration but also understand their reasoning completely. Many good points have already been made here and they are just as valid in the automotive world. I refuse to work on anything older than 25 years old with very few exceptions. If I do make an exception it has to be bone stock in very good condition and something with parts that are readily available, like a pick-up truck, that we have been maintaining well for years. Even then at least half the time it costs me more than I make, and I regret it. I don't like having to spend half a day driving around Houston looking for something in a junk yard.
Oh but all the parts are available! Every three steps something else breaks, strips, is found worn out of specs. You have to stop, see what the parts available are, make an estimate, call the customer and listen to them for another 10-20 minutes discussing if the vehicle is worth it, how much it cost 20 years ago, how much higher will it go? bla-bla-bla.
So, now I tell them leave me at least twice what I think it would cost 20 years ago, and if there's any money left over, I'll refund them. That way I can just get it done ASAP. Those that want their stuff fixed and can afford it are happy, the ones that will cost me money and then complain online (guaranteed) for my efforts leave and take it to a shade tree where it is usually permanently ruined. If you can't do it yourself, learn how or do what you have to do to find the right shop that will, pay them what it costs, wait as long as it takes, don't call them all the time and bother them, and be glad they're around. This is easier said than done, most or getting older like me and like said above, want to spend time riding, not wrenching. The bigger a pain in the *** you seem the less likely someone will take you in.
Don't get me started on the absolute lack of qualified people to employ. I was getting a sub sandwich Saturday and one of the young guys working there asked me about what I was doing (dressed as mechanic working on my own truck) and says he took auto shop in school. You better believe I told him to come talk to me and there's a lot of openings and money to be made in the industry. He seemed unaware of the need and interested. I don't get why he's making subs but I'll find out.
Or just buy a new bike every ten years, if I weren't who I am I probably would.
Vernon