In London it is now just a toll. It started off at just the busiest times but now you need to pay it 24/5, and even on Saturday and Sunday afternoons when there is no rush hour. Not only have the hours expanded, but so has the size of the zone. So now even right out in the suburbs you need to pay if you drive a diesel but I fully expect them to include petrol cars, then eventually all EVs too.
The prices are quite cheap too - the price is like 2 adults return tickets on the tube so you may as well just drive it since the price is the same but public transport is so utterly utterly awful and unreliable and slow and dirty and just terrible in London.
If they were serious about changing people's behaviour and serious about trying to prevent congestion and/or pollution they'd price it so that it is a real deterrent to usage (so instead of £15, it would be like £250/day or something). But if they did that then no one would pay so they'd not get the revenue. So they price it just right so that people pay.
They say all the proceeds are ring-fenced for reinvestment etc etc. This is disingenuous - it's not like transport suddenly gets 125% extra funding, they just set the budgets so the "extra" they get from congestion charging and cameras etc tops-off the budgets so things balance out at ~100% of what they'd get anyway and the difference just used for other vanity projects by TfL.