In short the answer is this: you have two companies selling you boxes, one that it’s literally impossible to look inside, and another one that’s very easy and encouraged to do so. Even if you know nothing about bombs, if both those boxes claim to not explode, which one do you trust more?

It’s sorta the same thing, it doesn’t necessarily means that the closed box is inherently less safe, but even if you personally haven’t verified that the open box doesn’t contain anything dangerous you can be somewhat safer in the knowledge that people COULD have verified it.