Why does a place charge a core charge on used parts such as br5ake rotors and also why do they charge an enviromantal fee when you're taking things out of the enviroment and putting them to use?

Most likely it's because they know ppl will be replacing parts already on the vehicle they are pulling parts for and use the core for an incentive to bring the other part back for disposal instead of the ppl throwing recyclable parts in the trash that ends in a landfill somewhere. They charge an environmental fee for proper disposal and to help with environmental cleanup for their business and just in case ppl decide to not to bring the core back for proper disposal. That's my best guess

When I worked at a junkyard a company comes in and buys certain cores such as your calipers rack and pinions and brake boosters and other odds and ends so that way they get the part back and they can sell it back to the core buyer environmental fees to help keep the yard clean

That seems to me like some very uniquely thought out questions. Unfortunately I dont have those answers. I wish I could help.

1999 grand marquis,problems concerning the brake cylinder cap gasket,replaced ,it developed a small split in center,2 weeks lasted,bled front brakes,seemed ok,until brakes went to floor?