The potential reasons are many and varied, like the cities themselves. For example:
Most cities in Europe ALREADY had mostly electrified public transport systems, so gained no extra effect for replacing diesel powered units. (Which was a separate decision from CC although one could argue they were linked.)
Different patterns of mass transit useage/bike use/walkability, therefore its hard to compare apples with apples.
Other countries are more decentralised so the effect of WFH was distributed across multiple cities not one behemoth.
Their mayors are not under such pressure to show a good result.
I'm not claiming there hasn't been a fall in pollution - there patently has. But just as you can look at the figures in two ways - as an increase in air quality, or a decrease in how pollutedly sh1t the air is - you can also pin the award for success on different factors when in reality it's a combination of things.
Kind regards
Ian
Each city is different. When I first came to Zürich, I was amazed to see trams on the streets. I only knew them from my Grandparent's stories and the museums. Now with ULEZs and all the traffic restrictions, London has a chance to re-introduce them.
Luxembourg reintroduced them five years ago and made them free to use for everyone... that's an approach that makes sense to me.
The London charge system is frankly nothing short of a trap - I think I am a reasonably intelligent person, I knew there was this thing, looked it up, worked out where the hotel was and tried my very best to comply... to only get charged anyways as I apparently managed to avoid the CC but somehow somewhere crossed an ULEZ line without knowing it. In a non-diesel car which gets a green sticker in Germany... laws and regulations are great, but the London approach is basically an intransparent mess.
Amsterdam for example offers clearly marked large car parks on the outskirts with security, lighting, video surveillance and great train connections to the central station. Something you wont find in either Zurich or London.
To be fair in Zurich long distance train travel also works, so park-and-ride would typically be to your local station not Zurich itself.
Obviously everyone knows UK trains are awful (even assuming the track reaches the city centre) so they're not much help. I've tried park-and-ride in a few UK cities and it is consistently awful; the buses were infrequent, slow and dirty.
So the summary is:
Register the car for Congestion charging and no need to register for ULEZ as the central authority will know from their control database it’s already compliant.
The public have already become a semi-slave to the system, it’s just a matter of time until we all become fully enslaved to the system.
"Register the car for Congestion charging and no need to register for ULEZ as the central authority will know from their control database it’s already compliant."
You are making an assumption here that the two systems are linked up intelligently...
While you can register for both on the same website, I would not bet that what you describe is the case.
Kind regards
Ian