I've been riding my bike to work along the same road for 15 years. I used to have to hold my breath along some sections of my ride. Now the air in the city is almost as fresh as in the countryside.
(I'd also guess that China had pretty lax emissions regulations in prior decades, making their "before" considerably worse.)
Not just that, they can mandate large changes.
If you try to do that in a western country, you'll have fossil fuel lobbyists, car manufacturers and a whole range of other vested interests putting pressure on the country's government not to make that change.
Democracies might be slow and misguided but in the long term, they are the best shot to correct previous mistakes.
But who knows. Chinese leadership was very smart in the past, maybe thell find a new way.
So if they can't afford to switch from ICE to EV mandate, they still have options to get around. Though I think if a person had enough money to buy an ICE car, they should have enough to switch to an EV in China.
With good reason too: Chinese cities had terrible air quality 10 or 15 years ago.
When I was in Shenzhen in 2024, I think around 80% of cars are EVs (maybe 90% now?). The difference in livability is so drastic compared to when I was there in 2019.
The air quality, heat, noise are all so much better that going to any city outside of China seems like going backwards in time. It makes a huge difference in Asian cities due to the density. The difference is probably less drastic in a city like San Francisco where the ocean breeze cleans the air more frequently and it's not hot. Maybe also not as drastic in highly sparse American neighborhoods.