I hear ya but hot tub service techs don't require the amount of training nor the amount of technical know-how required to work on a new car. They also don't invest in schooling usually nor have made the financial commitment auto mechanics have.
They don't "work" on the pumps or the boards as those usually are sent out or just replaced.
Not all service companies work that way. We have been told that several states and the NPSA are going to try to make it mandatory that you are certified to work on spas. Our techs have gone through classes before they touch a spa and we very much work on parts. Many of us(spa techs) are not "parts replacers" we will only fix what you need. Why buy a new pump if it needs seals, wet end, start capasitor ect?
Talking customers through it is pretty standard for us also, but did she diagnosis her issue or did he have to go out there anyway? If he was there and charging a fee anyway, might as well have him put it in.
As for mechanics and cars, I won't go to far there, but lets say the ASE certification certifies them to be parts replacers. We have a terrible time trying to find a mechanic that can actually diagnosis a problem in this area, just keep replacing stuff till they find the issue....except on my hyundai....great mechanics there. To bad they wont work on my Dodge or Jeep!