Part of a what a business owner does is sell a service and to me neither auto body or nail salons are commoditized.
Commoditization of a service is an interesting point if the tool's purpose is to compare prices and/or available slots. An oil change is pretty much an oil change, and I have no idea about nail salons, but as you say the cost to diagnose and repair "my headlights keep turning on and off randomly" probably varies by an order of magnitude depending on where you go, and it's unlikely you'll get anything resembling a real estimate on the phone without bringing your vehicle in.
Maybe you don't know enough about the quality of work of auto shops, or care, so are willing to go wherever can get you in, but then the question comes back around to whether an automated tool to compare options is doing you a service or actively leading you to a bad decision.
Example:
The AI assistant calls three places and says "My client has a 2005 Honda Civic and says the headlights are turning off at random times. When could you work on this issue and how much would it cost?"
Place A says "I can't honestly tell you what it'll cost, we need to do diagnostics first. We charge $75 an hour for diagnostics, with a maximum of two hours. That kind of electrical repair could cost $1500 if it's the control board, but if it's something simple, that could be fixed within the diagnostic period. I can work on it Friday, and unless a part isn't in stock, I'll have it back to you the same day."
Place B mumbles "Freakin' AI." then says "300 bucks if you're lucky. Drop the car off tomorrow, we'll get to it when we get to it."
The AI tells you "Place A will cost as much as $1500 and will take your car Friday, Place B charges $300 and up and can start work on it tomorrow." Or, more likely, it filters it even further, and just says "The lowest price and earliest availability are both Place B, who can do the work for $300 or so and start tomorrow."
I question how reliably, at least at this point, it will tell you that Place B sounds sketchy, like they don't care, that their estimate was half-assed, or that it's entirely possible that they actually will charge considerably more than that and that it could be much longer before they actually do the work.
Yes, you get information out of it that's technically accurate, but as always, how valuable it is is not necessarily that easily quantified.
And then eventually, the super-sketchy Place C figures out how this works, and just starts answering "We can do the work for as little as $50, and can start as soon as you drop your car off," and pretty soon the AI tells everybody that they're the cheapest and fastest option, even though they're lying to game the system.