The median BART worker made about $117 000 last year. Granted, that includes management, but it also includes part times I imagine that's much better than the typical BART rider.
The median BART worker is in about the 80-84th percentile of household income in the USA. Two 25th percentile workers made about $185 000 together last year, which puts our hypothetical couple in the 94th percentile of household income in the USA. Our strikers have more in common financially with a bunch of upper middle class professionals than the downtrodden poor stuck trying to find a way to work.