But we don’t have tariff regimes. That what a common market means. It doesn’t mean that you can sell the same product to everyone. It just means that you can move that product everywhere. And even the regulatory regime is overwhelmingly European (that’s why you get manuals in 20 languages)
You don't have tariff regimes within the common market, that's true. You do have tariffs on goods that are imported from any country other than the 24 in the EEA.
It's a lot better than having to deal with each county individually but still way more overhead than US.