At this time, the whole system seems to revolve around geographic location. As long as you stay put you're sort of fine, but if you move around within the EU, the law doesn't stay stable around you. This is impractical.
EU Inc seems to be a new initiative to fix a lot of the patchwork problems, but doesn't seem to be live yet. ( https://commission.europa.eu/topics/business-and-industry/do... )
I'm told that interstate commerce in the US isn't always necessarily easier, mind. Maybe the EU can take some lessons learned.