On-site auto repair is the professional version of "I know a guy who'll come look at it." The difference is the guy arrives in a service van with a dealer-grade scanner, a full tool set, jacks and stands, and the part you need. The repair is done to shop standards, just without the shop.
It's the same service whether the site is a suburban driveway, an office parking lot, an apartment complex or a contractor's yard with six trucks that need brakes. The mechanic adapts to the location; the quality of the work doesn't change.
Every city on Mobile-Car-Repair.xyz has a local mobile mechanic doing on-site auto repair with upfront pricing. This page explains what's included, where it works and what it costs.