Should there be a law

I find that driving and old car that hasn't been around for quite a while and finding parts for them to be challenging. i have a 1967 plymouth valiant signet with a 225 /6. not many are rebuilding them so parts are hard to come by. add to the mix of one year only parts and the price of those parts go up. and are hard to locate. i can find the rubber gasket for the front windshield for my car but can't find the correct rear one. but love my car and plan on having it for many years to come.