Re: Data point from (the other) Boston
Still, at $400/mo, of which my company subsidizes $200/mo…
That's eye-wateringly expensive for Europeans but the point still stands: priced correctly and operated well and many people will prefer public transport. In Europe subsidies are almost through tax so that they're not subject to the whims of employers and park + ride schemes are almost always free to encourage their use.
Here in Düsseldorf (a bit smaller than Boston) my monthly ticket costs around USD 70 and lets me travel with the family in the evening and at the weekends (and take my bike!) in a area considerably bigger than Boston.