Back in 2001 or so the plan for the next train line was for a heavily underserviced area here. It was delayed and instead a line was put in in an area with multiple busses servicing it. They finally put the line they originally talked about around 2 or 3 years ago. But it still doesn't cover as much area as the original plans were and rather than putting new trains for this line like the did with the other one, they took some from the line that services the farther away areas.
There are two big rushes of people in both directions. The trains and busses are packed always. The only reason I can think of is because they know most people commuting to work on transit have no choice. Where has people taking one time short trips usually do and they're trying to incentivise them to take transit at the expense of commuters.
It also just so happens those areas tend to have a higher percentage of wealthier people living in the and members of the transit board.