Common sense should prevail, but there will always be those that look at the cost and nothing else!
Tyres on a car that is garaged most of the time, won't have the same UV degradation and therefore hardening as ones sat outside all the time, and a car that moves fairly regularly even if it sits outside, will be different again.
Caravans and motor homes are the classic example of tyres that could be unfit for purpose in relatively short periods of time, as they sit for long periods in the same position, with tyres on one side of the vehicle generally deteriorating much quicker than the other.