Card fees are capped in EU, and I wonder if amex has any way of going around that. (0.2% debit, 0.3% credit)
https://eur-lex.europa.eu/EN/legal-content/summary/fees-for-...
https://eur-lex.europa.eu/EN/legal-content/summary/fees-for-...
https://politics.stackexchange.com/questions/48519/why-are-a...
High fees are what Apple uses to offer such “great benefits” with their existing card. If they want to expand to Europe, the only cards enabling that would be Amex, or Diners (which is even less accepted I think).