That's fair, but I believe cities can't be like that regardless. It's where you live everyday, the forests do not fix that. Your surroundings everyday affect mental and physical health (and these two interact with each other as well) and although a Sunday walk in nature is important, it will be negligible.

You have a much higher chance of living a sedentary life because you have to be in a car all day, so statistically less exercise, more obesity, worse quality of sleep (shown in scientific studies) all of which lead to mental health deterioration. There is also more noise pollution the more cars there are and the less trees there are, not only in the house(let's suppose you have good insulation) but also when you are out of the house. This is causing stress (you can't always realize this but it's happening), so high blood pressure, mental health issues etc. And of course air pollution. Besides all that, there are also less interactions with other people, less public spaces, so less socialization which is also a big factor in mental health and overall wellbeing. I personally really value the latter.

I'm not trying to throw shade to the country, I wish the way of life was better, cause I'd like to work there for some years and I'm not saying Europe is perfect, obviously the problems exist there as well but to a very lower degree. I could live almost wherever in Europe, but I can never live in the US.