That connection used to have a much higher service frequency and the traffic didn't support the costs of operating it. I'm not judging by what the traffic is n

That connection used to have a much higher service frequency and the traffic didn't support the costs of operating it. I'm not judging by what the traffic is now, I'm judging by what the traffic was when there was a dedicated BART shuttle to serve that exact segment at high frequency. Further, the timetable changes to increase service between that single station and the airport are large, therefore a massive amount of traffic would be needed from one station whereas improvements to existing service benefit people coming from the other 43 stations. So no, it's nothing like your analogy. And, even if the traffic would be similar to have an operating loss ratio similar to the other lines, that still doesn't address the fact that fundamentally it would be to provide service for transit users who live in counties that voted to reduce their BART service and opt out of that transit system. So in your analogy it would be like a Comcast customer complaining that when they use their friend's sonic.net line, the speeds aren't to their liking.