I blame Thatcher!
If she hadn't shut down the pits - the populations of East Durham (and those working in the area), would still be using the services that went to each and every one of the colliery villages in the area.

Since the working population (those who do work) now travel away to out of town call centres or industrial estates, the demand that existed for public transport through to Sunderland has waned.
Just look at the old United or TMS timetables to see the reductions over the years.

ANE have down the same route others have and have focused routes down certain core corridors throughout East Durham.
IF (and it is a big if), ANE managed to keep the tendered work or adapt it when taken on commercially, I have a feeling the entire network across that area would be totally different.