Doesn’t account for the cost of helicopter landing platforms at every station, for one. Or the cost of building additional helicopters to meet current BART scale, or the cost of the number of accidents you’d have once it scaled, or the cost of having all transit halt whenever there’s an air incident, or literally anything about reality. Like, are you people being serious or just smirking about your spherical helicopters?
His point was that Bart's current cost are HIGHER per passenger mile than the current cost of a helicopter, which is a notoriously expensive form of transportation (and also one of the most convenient).
Note that a 12 seat private jet also costs less per passenger mile than BART does. That's not beacuse jets are cheap, but because BART is currently absurdly expensive.
The error is completely ignoring the negative economic externalities of NOT having public transportation and the positive economic and environmental externalities of having public transportation.