All the cities you listed end up using the common EU standards for deciding emissions requirements, they just draw a different line as to what is allowed and from when. So maybe in one European city you need at least Euro 4 Petrol since 2024 and in another it was Euro 3 by 2025, but all you need to know as an owner or driver is that you're driving say a Euro 6 Petrol car or that the second hand car you just bought your teenage daughter is only Euro 4.
France has a layer where they translate from the Euro standards to their own system, but that's no different from having to mentally translate temperature units or distances.
Do you? Can you list say, three European countries for which you need a different sticker?
There are 27 EU countries, so if it's "a different sticker for each country" that seems easy enough, except, all the ones I thought of do not require stickers so...
Every euro city seems to be able to set their own regulation on car exhausts
So why not limit the sizes of cars or prohibit specific cars into the city?
I’m frankly surprised Amsterdam didn’t ban some of these huge machines yet
I detest how each city has different rules on exhausts but it might be the only way