The big difference is that, historically, there wasn't much you could do in a US bank's online banking other than checking your balance and maybe initiating a wire transfer (which usually costs double-digit USD amounts in fees, so it can be economically secured by manual human fraud investigation for every case).

By contrast, all European bank accounts offer outbound payments, which nowadays clear and settle instantaneously. The fraud risk is just orders of magnitude higher.

The US now has Zelle, which is actually showing just that friction and not going especially well for banks that were kind of blindsided by the sudden requirement to actually authenticate their customer, which is why you see all kinds of strange stopgap solutions mixed with proper security.

In the EU, banks are AFAIK banned from using SMS 2FA, and the 2FA needs to be tied to the specific transactions. Which nowadays de facto means a bank-specific (sometimes country-specific) 2FA app, possibly with the alternative option of purchasing a pricey dedicated 2FA device.