what's stopping then from saying "shove your taxes" and moving
Nothing really. I'd say: let them go. When they don't serve the society, why would we need them here?
Abolishing all taxes would give most companies a big advantage on the global markets, the country they're in would be kind of a tax haven.
I didn't see anything about taxes on imports yet, but that would be the traditional solution.
Once hired, these absent workers would still be required to work in some capacity, because no company is going to pay people to not do anything and not even warm a seat
Not now. That'd change when they wouldn't hire them for productive reasons but only to avoid their endprices being too high for the market.