why do you think they accept it for free its worth a lot of money as fuel or other use
Because they feel they are providing a "service"
They should be purchasing it.
Growing up, we use to dump our used motor oil in the 'fields' behind the house.
Today, I am more then happy to drop the used oil at any auto parts store / seeking forgiveness for my sins
How much profit does the store make on a drum ?
1) They have to dedicate floor space for any drums / which could be 2-3 pallets
2) Have an employee empty the containers into a drum
3) Discard the empty gallon containers
4) Deal with any spills
Let them make any profit they can.
When I shop for parts, I have a lot of options for getting the best price and quality.