What you are proposing is a good thing (greater efficiency) with a negative side effect (tilting economies towards the rich) but rather than tax the bad thing, you're taxing the good thing in order to reduce its negative side effect.
For whatever reason it seems like taxing robots is more socially acceptable than taxing the wealthy.
But these two often overlap. If any actual revolutionising automation by robots is coming, only the wealthiest corporations/people can and will afford it. As your parent poster said, robot tax is just trying to make sure that they won't hold on to their money under the mattress until the end of time. Redistribution of wealth is critically important.