I can see the case for it, I mean, I don't go into a car dealership and approve or deny which parts are to be replaced or which procedures are necessary. I have no basis for knowing.

Yes, but if you insist, your mechanic will probably still do what you ask them, as long a you pay up.

I’m 50/50 on this. The dealerships can be mindless flow-chart followers:

It’ll say “When A occurs, try replacing X” and they’ll do that, even though my notes stated that I switched all the Xs around and the problem didn’t move with them.

Yes. And sometimes I even want a service provider that insists they know better. (Eg I frequent some coffee shops like that.)

The crucial thing is that there are alternative providers where I can get exactly what I say I want, and get it.

As a former mechanic, at least my shop would occasionally refuse to let a vehicle leave the shop- the one example that I remember most clearly was a SUV that came in for an oil change. The owner was planning on a 800 mile trip with their family and wanted an oil change before leaving. One of the wheels had a serious suspension problem, and would likely fall off shortly & cause a rollover.

We weren't going to let that truck leave our shop w/o getting fixed, none of us wanted dead kids on our conscience. We extended credit to the customer & cut our rate so the owner could afford it. Point being, in this case we definitely knew better than the customer, somehow they didn't realize a wheel falling off at highway speed is dangerous. P

However, that was a very rare situation. If a customer insisted they wanted work done that we didn't feel was necessary, we would tell them so but still do the work if they wanted it.

Most would see that as an argument in support of paternalism, and as do I, which is why I agree with your position. Advertising drugs to consumers is akin to advertising specialty testing equipment to individuals: at best neutral and at worst harmful. You have no business self-diagnosing with a risk of stroke and running in there to demand Plavix. There should be no world in which the doctor goes, "Huh, Plavix! I've never heard of it, and if you think you're at risk of stroke, well bud, here you go, one years supply."