You do realize some countries in Europe have federal governments (Germany for example), right? And then these completely independent countries are part of the EU which have EU elections. So you have federation within federation. Also, the EU has higher population than the USA. We don’t even all speak the same language. We are allowed to move between EU countries whenever we like and have residence where we please.

I think its not Europeans that don’t understand.

It does not seem available on mobile. On desktop, it is an extension called “Temporary Containers”. You may also want the official “Firefox Multi-Account Containers” for managing sites where you want to stay logged in.

I use Firefox temporary containers. So not only are they deleted 5 mins after I close a tab, but different tabs don’t share cookies unless I explicitly allow it or the tabs are opened from one source (e.g. open link in new tab)