Oh do they? Never heard about that. Guess I’ve learnt something new. I wonder if it would be different for us, given how fewer big companies the EU has compared to the US.

Yes, for instance their equivalent of VAT is state-based, some of them having 0: https://en.wikipedia.org/wiki/Sales_taxes_in_the_United_States

Delaware is indeed kind of similar to Ireland: https://www.investopedia.com/articles/personal-finance/092515/4-reasons-why-delaware-considered-tax-shelter.asp

Both are listed as tax heavens on that page: https://en.wikipedia.org/wiki/Tax_haven#Lists