The point is not that they couldn't, but that a company moving proprietary "services" offshore as a means to cut costs aren't interested in whether the services can be provided locally, but whether they can cut costs by moving them offshore.

If you tax renting labour, then companies seeking to do this will just enter into long enough service contracts to have the outsourcing agency custom-build a SaaS just for you instead.

The market opportunity here is simply to be an outsourced body shop.