The thing about increasing the gas tax is that if it was enacted and everybody pretended not to notice nobody would actually care. My point is that gas prices fluctuate enough that if gas tax increases of the magnitude that are usually discussed - like 15 cents/gallon - were enacted then drivers wouldn't even really notice unless somebody told them. And, yes, I get that somebody would tell them and voters would probably get pissed off, though I think anti-tax politics isn't quite what it used to be.
Sure the gas tax is regressive. I'd probably prefer "soak the rich" generally as the plan to pay for everything. But contrary to popular belief, most of those roads are "subsidized" in the sense that they're mostly paid for with local property taxes, not "user fees" like gas taxes, tolls, and vehicle registration fees. Driving is cheaper than it should be, given the various negative externalities.