So it's a nice system. It's a shame that the US hasn't adopted it.
News and entertainment media will sometimes find an article of clothing with identifying marks in Africa and trace it back to the original owner as an anecdote for a story about some aspect of the industry.
But that aspect aside, there are slim pickings with respect to less casual attire in charity resale shops, especially if you stray too far from median sizes. Your best bet at finding a suit that you might actually want to wear is at estate sales for the recently deceased, or stores supplied by the unclaimed airline baggage clearinghouse in Alabama. The higher the value of the clothing, the less likely the owner is to give it up willingly.
I don't know who told you we haven't adopted that system. Tell them to look for a Salvation Army, they're like the Star Buck's of charity shops around here, there's one on every corner.
Secondhand - Thredup and sites like it.
Marshall's, TJ Maxx, Men's Warehouse, etc. You can also travel to Hong Kong, Beijing, or one of many other cities in Asia and have them tailored for much less than retail department store prices.