Are mobile mechanics a new thing in the US or is this different? Lubemobile here in Australia has been around for 30 years and I'm sure there are competitors.
Is it just the collation and quoting that's novel?
No, mobile mechanics exist in the U.S. However, the service providers are either (1) very expensive, top-of-the-line, and operate on the concierge model, or (2) not worth the gas they spent getting to you or whose skillsets are limited to very basic repairs.
Type 1 will not use YourMechanic because it will cut into their profit margins significantly and they don't need a 3rd party middle-man to get business.
Type 2 will use YourMechanic. They can handle simple stuff, i.e., the stuff that will take a shop 10-15 minutes to repair. For anything more complicated, your SOL.
Is it just the collation and quoting that's novel?