They had one of these in Austin Tx in the 70’s while I was in graduate school there. I used it several times, including getting lots of good advice from a mechanic who was also likely the owner. My guess is they didn’t make a lot of money from folks who only took problems in they could handle, such as my wheel bearing repacks, starter motor changes, and so forth. The big money was in charging for mechanics’ time when the owner got in over his/her head and needed to simply turn it over to a professional.