In a properly built landfill, yes, it does just sit there, and does not leach into groundwater -- and if you think municipal landfills have only a plastic liner to protect the groundwater, you maybe ought to learn a bit more. [snip]
That's what I do, too -- but once the job is done, I get as much paint as I can out of the roller cover and back into the paint can, and then the roller cover goes straight into the trash.
For latex paint???? ROTFLMAO!!