Uber's drivers pay tax on the fuel they use and there's sales tax on the transaction itself. They are, in fact paying for the use of the roads. Why should there be a special additional tax on that particular type of business?

Because everyone else in the business is still paying a special additional tax? If you disagree with that, you have to fight to change it for everyone. You don't just start competing without paying the same taxes as everyone else.

At first, that sounds more fair, but in practice it means a lot fewer people would start doing useful things.

Earnest question: have any of Lyft et al tried to just say "okay, we'll pay the tax, give us the form to fill out"?

Do UPS, FedEx, etc. pay separately for the privilege to use these roads? No. The money to pay for these facilities comes from gas taxes (mostly), sales taxes, income taxes, etc., all of which are paid by the Uber/Lyft/Sidecar people too. Their cars don't run on air, you know. In fact, Uber's limos use much more gas than the Priuses that the cabs drive, so in fact at least Uber people are paying more for the use of these roads.

Businesses like Uber pay a lot for them. Corporate taxes, payroll taxes, sales taxes, gasoline taxes, business licenses, registration fees, etc. etc. Trying to justify every runaway regulation and fee with "oh, but we have to build the roads!" is only going to convince somebody who is too lazy to think about how many taxes business like Uber has to pay in any case.

And if by the "services" you mean blocking competition and being the enforcement arm of the unions - then I could do without these "services", thank you very much.