But is that based on research performed, or just a "better safe than sorry" statement? Have they (or anyone) ever seen a seat fail prematurely or perform worse due to being involved in multiple accidents? That page doesn't have any more information other than that statement. I'm having a difficult time imagining what parts of a car seat would be damaged during a crash (where the seat itself is not impacted). One exception is if car seats are designed to deform, crush, etc. to absorb energy, like a bike helmet is. But I've never seen anything like that.
Also, when trying to decide whether a second-hand car seat is safe, you're multiplying the probability of a seat being damaged in an accident, by the probability that the damage will significantly reduce the safety of the seat, by the probability that the seat being sold was in an accident. I understand if a parent would rather just buy a new one and not worry about this. But I see this as being a near-zero risk.
edit: I see that some child car seats do use EPP foam, which could possibly get permanently compressed during a severe impact.
Also, when trying to decide whether a second-hand car seat is safe, you're multiplying the probability of a seat being damaged in an accident, by the probability that the damage will significantly reduce the safety of the seat, by the probability that the seat being sold was in an accident. I understand if a parent would rather just buy a new one and not worry about this. But I see this as being a near-zero risk.
edit: I see that some child car seats do use EPP foam, which could possibly get permanently compressed during a severe impact.