We can tax corporations and billionaires. Building a functional education system isn't an unrealistic pipe dream, its an imperative for a well adjusted society.
(Also, only about a third of the incidence of corporate taxes falls on shareholders, with the rest being split about equally between lower wages for workers and higher prices for customers. It can be surprisingly regressive!)
- There are many taxes, not a single tax rate
- It completely ignores the idea of progressive taxation: rich individuals and giant megacorps can afford to pay higher tax rates without the same issues that would occur by applying those tax rates on lower and middle classes and small business.
- It cannot be empirically validated without cherry picking data because it ignores many crucial factors.
It's basically just propaganda paid for and promoted by the rich to convince the proles to let them keep more money.
But you are obviously not the first one coming up with this idea. Plenty of people have tried and are still trying, and it still does not work (it does not mean we should not try). In the meanwhile, we still need to improve the situation for people who are being the victim of it.
This is why this measure has been created while your measure is still far from being reality.