I see it more as the paragraph after that explains: that EU sells itself as a single market, yet there are different rules depending where in that "single marke

I see it more as the paragraph after that explains: that EU sells itself as a single market, yet there are different rules depending where in that "single market" you sit. In the US you kinda have the same issue, except that since the US is bigger geographically, you can create hubs that mostly share the same rules.