There's a chicken and egg scenario, too. The 21 and x21 used to run 6 times an hour from Durham. Ignoring the improvement just before the pandemic when that was weighted more in favour of the X21, we are still down to 4 times an hour. When they all run.
Pre pandemic, I'd happily run into Newcastle twice a, week. Now it feels like more of a faff with a lot more clock watching and it is twice a month at best.
RE: Reversing the decline in passenger numbers