Why do you assume that? I bet most people don't know their barber personally, and just go to the shop to get a cut. Should getting a haircut be fraught with having to go online and read a bunch of reviews, followed by the inevitable bickering between fake reviews and fake responses on top of that? No, I just want to get a decent cut for a decent price. We can nitpick over how much training is reasonable, and sure there's an element of protectionism there, but if the Internet had taught us anything, it's that online reviews are bullshit. I would hate to have to rely on them to correct for a bad practitioner when they aren't really able to do anything about bad doctors, which has a much higher bar to practice.