This isn't a new problem- I once got a PAL DVD instead of a US one years ago- glad I noticed before I unwrapped it.
It is a problem borne of unscrupulous seller, unscrupulous customers doing returns, and a marketplace that doesn't always do quality control.
As a general rule, I don't buy older games from Amazon anyway due to lack of photos- your 'good condition' and mine might not be the same, I want to SEE the game! At least Amazon has a very favorable return setup, & it's pretty easy to prove a wrong region game is not as described.