So the vendor quotes a job, but can't inspect/verify ?How is he going to measure it ? Without very specialized equipment, you can't. CMM doesn't cut it.
It's like heat treating, only worse. Most people don't have Rockwell testers and have to go by what the heat treater says. If the heat treater messes up, how will you know ?
Gear measuring equipment is way more complex than that. I've only had one or two customers in my entire life who could measure the gears I've made.
Another problem is, all those numbers that software puts on a data sheet ? Pretty much meaningless. There's only a couple that actually have any effect. So that's also another layer of b.s. in the process.
Maybe the OP should send some of the gears out to a place that can verify those numbers "independent Inspection".