As a practical matter, no country could subject citizens of different EU member states to different visa policies if they all had identical passports. That's exactly the situation with American passports.
Yep. And then you get disagreements and tit-for-tat. Just don't claim that the US's policies are in some way more legitimate.
> then it should stop holding
Says who? On whose authority? If the US wants its citizens to be treated uniformly, then it shouldn't give out per-state driver's licenses.
The authority or reasonableness and practicality.
> If the US wants its citizens to be treated uniformly, then it shouldn't give out per-state driver's licenses.
It may be news to you, but those aren't travel documents and are nonstandardized to boot. But if you think the EU should wade into that mess, I guess you're entitled to your opinion.
Also, it's probably worth noting treating Americans as citizens of their state and not the US for immigration purposes is totally unprecedented in the modern era of passports. On the other hand, the precedent over the same period has been to treat Europeans as citizens of their member states and not of an undifferentiated EU.
It's fairly close to how it works. If you live in Montenegro and need any EU visa, you go to Slovenian embassy. Even if you'll visit Spain or Ireland.
So does the European Union.
US states have no foreign relations. There's no Californian embassy in Sofia, but there is a Bulgarian embassy in Washington. No American travels on a Californian passport, but Bulgarians travel on Bulgarian passports.
If you want foreign countries to treat the EU as a single diplomatic unit, then all the EU member-state embassies should probably be closed and replaced with EU embassies, and all member-state passports should be replaced with generic EU passports.