Working in music retail gave me a different perspective. We sold basses from the 3 brands you mentioned, and would pretty regularly re order popular colour combos, for example. It's not like we sold loads of US Stingrays, but I know for sure there would have been several examples of the same spec/colour in the same town, so when you expand that globally it's not insignificant!
I do think more people hold onto quality instruments than perhaps we assume; being members of this GAS - inducing den of disrepute (Bass chat) I think warps the perspective a little 😂