Taxing robots rather than people. Scott Adams thinks this is a great idea. He has promoted the idea on his livestream several times, suggesting that this is an alternative to income taxes.
The biggest flaw in this is something that government supremacists won't see as a flaw: it would continue to fund the state.
The second problem is, it's still really taxing people. Just taxing the people who own the robots. This is still unethical in the extreme.
Even if robots have jobs, and you steal a percentage of their productivity in the name of taxation to actually support the people of the country, this just adds an unnecessary layer to the process.
Instead of doing the stupid thing, have a robot work and send some of the profits of its productivity directly to someone or some program in need of funding. And do it voluntarily or not at all.
Don't reverse-launder the money by sending it to government, where much of the value will be diverted away from the thing it should be supporting.
Funneling things through government bureaucratic layers of crookedness and inefficiency means those who need the help get much less of it.
Anything which props up government is part of the problem.