Take 15K miles/year at 4 miles/kWh or 30 miles/gal. 3750kWh or 500 gallons of gas.
At MA electric rates, the electricity is $750, the gas is about $1500. It's unlikely that an electric car consumer would pay more than the $750 delta for the electric charging spot, and would likely be willing to pay only a smaller figure because they are unlikely to do all of their charging in that space or network of spaces.
That premium/willingness-to-pay won't even cover the all-in cost of installing a single EVSE in the first year.
Barring significant over-subscription, that's still a ~10 year payback. With massive over-subscription, it doesn't become a reliable charging source. (My prior post, which I'll leave unedited, was unclear/insufficient in stating it was longer than a one-year payback.)