With my DD, we had an ISOFIX carseat. That sucker wasn't going ANYWHERE.
Now we have a different car and are expecting our second and our car is not ISOFIX compatible any more, and every carseat I try to use with a seatbelt fitting feels SO wobbly by comparison. Even when Halfords showed us a fitted one, rearfacing, no movement backwards but wiggle room side to side and can move forwards (i.e. towards the back of the car) when shoved.
I'm so used to a car seat literally having no more than an inch movement either way no matter what I do to it that every carseat looks massively unsafe by comparison.
Watched loads of YouTube videos etc. but none of them show the car seat being pushed back towards the backseat.
For those of you without ISOFIX carseats, how much movement does your carseat have?