In this case, the concepts would likely overlap.
Taxing large endowments would cause wealthy universities to slash financial aid and charge more tuition. Harvard doesn't even charge tuition if your family is middle class (less than ~$125 income) or lower because it has a huge endowment and can afford those kind of things. For profits have no endowment and charge almost everyone full freight. Hardly the desired result. Most of the really bad universities out there (the ones that don't get graduates jobs) don't have huge endowments.
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).