Just because the concepts are sound, how do you know the ladder was well-constructed, doesn't have any damage that might weaken its structure, etc? You need to

Just because the concepts are sound, how do you know the ladder was well-constructed, doesn't have any damage that might weaken its structure, etc? You need to trust the company that built the ladder to make quality ladders, and you need to trust the individual ladder to not have any major faults.