Enterprise is probably the most unique of the majors in this regard. Enterprise is actually split into 50 or so smaller companies. (It's easiest to think of them as districts or regions, but Enterprise actually incorporates each individual "district".)

Each Enterprise "district" owns its own fleet, and those cars can be passed around and/or rented one-way freely between the branches within the district. Occasionally the districts have branches in multiple states (i.e. you may see a Kentucky plate at an Indiana branch) but often times they don't (the NYC, Los Angeles, Miami areas are large enough to have their own "district").

A one-way drop outside the district will usually be retrieved by the owning district. If that's not cost-effective, the car will usually be sold, either to the district it's currently parked in, or on the used car market.

This is why Enterprise has such goofy one-way policies. For instance, you can one-way a car from SDF to EVV, but not from MCO-TPA.