The gas tax works. It's hard to evade and benefits from existing taxing infrastructure. The only problem is that it was never indexed for inflation. Tell me why we need a completely new system? Are people really less resistant to this than paying a few more cents a gallon at the pump?
Electric vehicles and hybrids can't be the reason. Electric vehicles still represent a tiny portion of vehicles on the road. Hybrids don't really get much better fuel economy than the tiny econoboxes of the 90s. People still drive big trucks everywhere. Since less fuel efficient vehicles also tend to be heavier, they cause a disproportionate amount of road damage (and effectively get taxed more per mile).
Don't hate the player, hate the game. Pay is a function of supply and demand for talent.
Medical research is done by teams- no one person is going to "cure cancer" by force of sheer intellect. If such a thing were to happen and that person had reasonably good business sense, that person would easily become the wealthiest person who ever lived. What actually happens in the real world is that hundreds of researchers, who are actually mostly pretty fungible, perform years of grunt work to come up with a drug that marginally increases survival rates. The company keeps most of the profits because the company is what organized and bankrolled the effort in the first place.
In entertainment, the phenomenon of one-person brands means supply is necessarily limited. Only one person on earth can be Mr. Burns, and a lot of people want to see Mr. Burns. So if you want Mr. Burns on your show, you had better pay that person a lot of money. By contrast, there are hundreds of thousands of medical researchers, who are all willing to work for low six-figures or less. They, in turn, make a lot more than fry cooks, a job which just about any reasonably healthy human can perform with minimal training.