Raise fares to pay for the system. Subsidize fares for the poor through welfare and the middle class through tax breaks and not through subsidized fares to obscure the real cost of the system. Putting more of the power of the purse back into people's hands is the only way to ensure that the transit system is responsive to the needs of paying riders and then transit expansion is about economics again and less about politics.
The same could be said for automobile transportation. Automobile transportation keeps becoming more and more subsidized, as road costs keep increasing but use taxes (aka gas taxes) aren't being increased at the same rate.
On the other hand politicians have been more eager to raise public transit fares. What this does is incentives people to drive over taking public transit, and that is bad for traffic congestion and sustainability in the region.
So you can't look at transit like it has no competition, it most certainly does.