You're going about this the wrong way. You're expecting him to drag his tools, an air hose, and a hoist to each car? They are set up to do inspections in their shops, just like doctors do with people. That's where all their equipment is.
Trade-in cars were all inspected at the new-car dealership where I worked. We were allowed one hour to inspect the brakes, steering and suspension systems, and all optional equipment, and to make a list of needed repairs, and another 20 minutes for an oil change. Later we got normal times for any approved repairs. In particular, the used car manager knew any Ford would need a lot of steering and suspension parts replaced to make them safe for a little while, and any GM would need electrical repairs and would have to be taken to the GM dealer down the road to have computers programmed to the car. The stupidly high repair costs is why GM owners usually traded in their car.
To do an inspection on-site is something you can do yourself with a little knowledge and training, but to be thorough you'll need a floor jack and jack stands. If your mechanic isn't planning on bringing those items he's just going to do a quick once-over which can leave you with a lot of unexpected repairs later. Using a floor jack will take him three times longer than if he had the car on a hoist. Hand tools will add a lot more time to the job. He will be lucky to inspect one car in an evening.