Why complicate things? Existing taxes are the ones which it would be sensible to start with, and existing taxes on things which we can't easily make more of (land, air, water etc.) are the sensible things to start with of those again.

Skilled labor is not currently taxed as a specific thing, and we can make more of it by educating people, so why on earth bring that up unless it's a setup for some odd rhetorical point?