Yes, the risk you’re talking about is socializing losses, a big problem in our society today (mainly in the financial arena). I covered that issue in my post, though- tax corporations commensurate with their abuse of said systems.
That said, your analogy to the postal service is an interesting one, although the cost of that is so low per person that its effect as a regressive tax is probably trivial. It also benefits from near zero bureaucracy, unlike most attempts to apply user fees to roads. The point of supply is easily controlled.
Water is a little fuzzier. I grew up with flat-rate water, and a lot of places still do that. The whole notion of “too cheap to meter” as was promised with nuclear power. Of course, flat-rate-anything is pretty much always a regressive tax also, so in this sense a user fee might actually benefit lower income people.
The main point I was going for was that all current user fee systems on roads (gas taxes and tolls) are very much regressive taxes because they are high relative to their single-use utility. A tech worker doesn’t sweat $5 a day to take 20 minutes off their commute on a toll road, but that’s crippling to a dishwasher. We’re not talking about buying stamps here. This is luxury pricing on life-or-death goods.
A better analogy for me would be healthcare. The current system works fine for people who can afford it, but is a nightmare for those who can’t. If we agree healthcare (and roads) are a critical public good, then the system of progression taxation that we all agree is fair is a great way to pay for it. Social systems are about leveling the playing field, and use of roads is a clear case where that is needed.
