I can understand this for companies not in the EU. But within the EU it seems to me that it's just inertia -- as far as I know, if you're an EU resident you can

I can understand this for companies not in the EU. But within the EU it seems to me that it's just inertia -- as far as I know, if you're an EU resident you can work from any EU country for 90 days with no changes to tax, insurance, social security, etc. required.