We already have a similar organization - Underwriter's Labs - that examines electrical appliances and apparatus and if everything is grounded properly etc it receives an "UL Seal of Approval"

It is entirely private.

A domestic proof house that is a "real" proof house (not just some shade-tree smith that puts a few hot loads thru a gun) would serve a useful function - I can envision buying a good older shotgun with the sale contingent upon the gun passing proof. The seller could refuse, of course.

There are a lot of lengthened 2 1/2-inch chambers on some fine English guns and it would be much easier to send them to a domestic proof house than back to Birmingham or London.