They're all going to the same place, but all coming from different areas. Arranging for them to get to a common point to even board the public transportation you're offering would require them to take a car, since density makes and sheer time makes it prohibitively expensive. If buses did stop in convenient locations for the widely dispersed people in small towns, it'd take hours before they'd even approach their destination after having spent half the day just picking up people from all over.

The only way to fix the problem is to encourage people to move out of the suburbs and small towns and live in denser regions.