From 2pm until closing, everyone traveling to or from TL must transfer at Epcot. Buses run between Epcot & the Epcot Resorts during those times so that Epcot Resort Guests can make that connection without walking thru the park or making 2 transfers. What's confusing is that if you look at the signs at the resort bus stops, they say "Bus Transportation to MK, AK, and DTD," "Boat Transportation to Epcot & DHS," and then down at the bottom, "TL - after 2pm take bus to Epcot."
There's also a bus from Epcot to the MK monorail resorts during those times, so that those Guests won't have to transfer twice (bus + monorail + monorail.)
It's inadvisable to depend on those buses just to get to Epcot, since if TL were to close early due to exceptionally bad weather or a technical problem, Epcot would probably pull the buses off that service.