I'm curious how much of that is Porsche dealers looking for an excuse to do expensive work.
Which its kinda funny even Prius Chat (think that's the forum) has a mix of people "don't do this yourself just have a mechanic do it" and then people saying that its mechanics trying to scare people into not doing work themselves. Which there's a bit back and forth in that sure some people will be better off versus screwing it up themselves and then having to pay for a mechanic to fix it and possibly other after, but some stuff it seems like mechanics do try and scare people to get some extra business.
The most vulnerable are the ones who have no understanding of the vehicle; and do not have the natural inclination, time, or ability to "figure it out" and DIY . There is also the matter of "necessity"; if a situation occurs where the car won't run, that's when a bad mechanic can tack on "extras". Women of any stripe, men that dress and behave in a way(such as dress too wealthy, opening yap about "what they do" or state they are "educated") that indicates they have no knowledge of cars, language barrier are all factors if a mechanic goes "full predator" or not. A physically disabled person is also more vulnerable, as the might have the tools to drive the car, but not to loosen fasteners, operate equipment, etc that only some with a pair of hands can do.
Reporting to the authorities will be rendered partially ineffective, since they already know egregious misconduct. There's also a matter of time to write out the complaint.
For every Eric O, of South Main Auto Repair Youtube channel, there's a bunch of "money extractors" out there along with quite a few incompetents; some of his video content is from the result of fix problems others couldn't or were created by another.
There are good guys are out there, but finding one can be a (very long chain of) gamble. The local Toyota dealership hasn't given me warning signs that they'd screw up the insides of a car, but the ones running their own shop have given me more than enough experience to see that there are real POS out there .After all, total dollars made is a function of quantity of transactions/hours multiplied by the price per transaction. The more jobs done, the more dollars coming in.