I don't know for medical labs but for other types of labs, there are accreditation bodies that ensure quality/process/etc meet standards. Instead of the verbal vomit of requiring a test with no criteria attached, it would have been reasonable to list the accreditation bodies around the world that are acceptable. That way you don't need to go all the way to the lab level in every country. EG A2LA, accredited to ISO 17025 etc (those do not apply to medical labs but they were a few I knew). Still not perfect as dodgy companies could pretend to be accredited and then disappear but at least it gives consumers something they could look up to see if they are going to "dodgy steves lab" or a company that has been around for a long time and tries to do things properly.
With WSIB you go to their website and verify coverage. You don't need to trust a possibly altered document from a supplier.
Get your info from the source. I can't see any reason test results can't use a similar protocol.