If they reconfigured the bill and made it clear that the $12 a month was to maintain the grid, and it was the same for everyone, I would be fine with that as a fixed cost to have the grid available. Maybe have tiers for the size of the grid service. A fee based on single phase 120/240 at 100 amp, a bit more for 200 amp, more still if it is a 3 phase feed, etc. That makes far more sense than trying to charge people with solar an extra fee to help people who can't afford solar. I did some work in a very rich person's home, the house had a 200 amp panel for the garage and guest house, and a separate 400 amp panel for the main house. and pool building. The house also had over 20 KW of solar panels and I saw at least 4 Tesla Powerwall2 units as well as at least 4 A/C outdoor units. The mechanical room of the main house had 2 huge 100+ gallon heat pump water heaters. The garage had 4 EVSE units. I don't know what cars they had. Under my idea, a home like this would pay a higher flat fee to keep their 600 amps of grid available compared to my 100 amp feed.
Under the current rules, my system is able to zero it out and I am paying nothing. My credits built up and are paying the extra fees right now. I will do that as long as I can, but I do see how people without solar could see it as unfair. In a way, I am "paying" for it, as I did supply the grid power at just $0.065 per KWH to pay those fees. And it cost me quite a bit of money to be able to do that. All at the same time, if I do need to buy any power, they bill me the peak rate of $0.57 now. That is nearly a 9:1 ratio.