[FooBarWidget]

But the US has thousands of different tax jurisdictions. Even US lawyers have difficult time giving fast, proper answers on inter-state tax matters. Law and legal readings change every year. How is the US in practice a single market where you get other states "for free", other than language?

[Amfy]

language and culture is a much bigger factor than tax. Tax is solvable by throwing money at accountants and lawyers.

Language and culture, you cannot force to change. Something people love in Germany, most likely will not fly in Spain or Greece.

To drive demand is much trickier than solving tax issues.