Anecdotally this rings very true for me. Dealing with car seats is one of the most annoying and cumbersome issues of being a parent in the US.
However I will also say, for the sake of other parents who may be in a similar boat: Diono Radian carseats fit 3 across in our Mazda 3, which isn't exactly a big car. So if you find the right seat, you can make it work.
The biggest problem is the infant period where they have to face backwards. For that we went with a Cybex Aton 2, which was sufficiently "vertical" that the front seat passenger could sit comfortably. Everything else we tried required the front seat to be shoved way too far forward.
The Joie i-Snug 2 is the one infant seat with a snap-in base we found that would fit in our 2008 Ford Fiesta and allow me (1.65m) to sit comfortably in the front passenger seat. My husband (1.85m) can fit in that seat, but we’re not sure how great that’s going to be for long drives where we need to switch drivers.
We’re in Germany, which appears to have similar car seat rules to the US, along with increasingly large cars, but without home or public garages that are growing at the same rate. I’d like to replace the Fiesta with a hybrid Corolla wagon, but the current model is 5cm too long for our garage from the 80s.
However I will also say, for the sake of other parents who may be in a similar boat: Diono Radian carseats fit 3 across in our Mazda 3, which isn't exactly a big car. So if you find the right seat, you can make it work.
The biggest problem is the infant period where they have to face backwards. For that we went with a Cybex Aton 2, which was sufficiently "vertical" that the front seat passenger could sit comfortably. Everything else we tried required the front seat to be shoved way too far forward.