It really isn't. I've got a 13 year old Toyota which is ULEZ compliant. I bought it for £4k in 2020. My previous car - a now scrapped Fiat Panda from 2007, was also ULEZ compliant. I bought that for £900 back in 2015. Obviously car prices have been changed by covid - but there are loads of compliant cheap cars available.
It's also only limiting driving within the city limits. You're free to drive anywhere else. Hardly totalitarian.
Ultimately though the ULEZ isn’t even going to affect that. The percentage of cars affected is fairly small and shrinking each year.