I think that restaurants with drive-thrus should be required to have a trash container along the path of the drive-thru so that motorists can dispose of their trash, which probably comes from the same drive-thru from a previous visit or even from a different drive-thru.

If a restaurant is granted the right to have a drive-thru (usually through local zoning rules), it should also be required to help cut down on trash problems by offering curbside trash containers.

I like the drive-thru trash container in the photo below which has a chute attached. This is at the Jack In The Box on Wilshire in Santa Monica.