[ethbr1]

Afaik, the bulk of the US' federal centralization of commerce is based on the Commerce Clause of the US Constitution [0], which based on reading (and more so on precedent) grants the US federal legislature the ability to regulate commerce between states. As most commerce crosses state boundaries, this de facto allows the federal legislature to define and enforce regulatory standards.

In practice, it's more nuanced and subject to continual back-and-forth arguing. E.g. California and Texas trying to decide their own standards, by virtue of their economic size, then hashing it out with the federal government in court.

I'm not sure what the EU regulatory cornerstone equivalent of the Commerce Clause would be.

[0] https://www.law.cornell.edu/wex/commerce_clause