It takes minutes to transfer a car seat. LATCH especially makes it incredibly easy.
"Sorry no, I don't have a car seat. And I can't get it from you today because it's with you at the office."
The permissible lateral movement specs can be hard to hit even if you know the tricks.
Maybe the first time ever, with safety anxiety it could take half an hour, but also any police or fire department will just do it for you.
"permissible lateral movement specs"? What manual are you reading?
So I don't think it's as easy as you make it sound - and I might even go so far as to suggest you check the lateral movement specs on your child car seat to make sure you are within tolerance. The rule of thumb seems to be no more than 1-inch side-to-side movement at the belt path [2].
I had this one single mother I’d take all the time and she’d have that seat in under two minutes, just clip the little hooks and strap in the kid.
Don’t know how properly the seats were installed because I honestly didn’t care and I never touched the things because then I’d be liable in the case of an accident.
Never once had someone take half an hour because I’d have been pissed for them wasting my time.