I read that article where @josefow said BART couldn't do fare inspections in San Mateo County. I mean, honestly the demographics of Daly City - Millbrae is mostly working class/ middle income Asians so it wouldn't be diversifying much but. . . Why can't they do it? I dont get it

Because the law that creates the transit district is 3 counties, not 4. So they can't enforce the rules BART created. But IANAL

So what, BART PD goes to San Mateo County all the time.

Regardless of what makes sense, the law does not give BART PD authority to enforce in San Mateo County. As a matter of basic fairness, I am committed to changing this.

This may be changed by amending the state law that created BART, the "BART Act", or possibly by working with San Mateo County officials. There is plenty of space to negotiate here.