Personally I think the idea of taxing robots/tokens directly is too narrow an idea.
Marginal income taxes are regressive now in the sense that folks with more wealth have far more resources to avoid paying them, but otherwise the reasoning seems less regressive than a consumption tax (e.g. VAT)
That's half the battle. The other half is closing all the loopholes and making stuff that used to be illegal, illegal again (e.g. stock buybacks).