Don't scare the Horses!

[Kalee20]

No it's not, it's about money. If it was about air quality, they wouldn't say the same cars can come in but pay for it - you'd not be allowed to drive in. 

That's not really the case is it.
As you have to pay a fine for go within ULEZ with a non compliant car it reduces the number of such journeys.

And it's not even a fine! (Which would imply wrongdoing). It's a day's permit to drive a non-compliant car in.

Ultimately, it won't reduce overall pollution, but it will avoid the high pollution concentration in central London.

Also there is little to no evidence to support it. TFL has been found to have misled the people and lied to the London Assembly then asked scientists to lie in a report after their report couldn't find any evidence to support its effectiveness. C

Now that's a different matter - I hope that's not the case, unfortunately falsifying evidence has occurred in the history of the world... Hopefully if there has been, it will be dealt with very severely.