The recipient getting their stuff stolen is a big deal for the merchant too, though.

Certainly for an expensive item, the customer may be out their time, but they are going to ask for a replacement or a refund or do a chargeback, the merchant is generally going to have to accede to the request, and the merchant ends up being out money.

So if the merchant decides to trade off security for delivery cost (by choosing a courier with a slack approach to verification), that's their prerogative and they are economically incentivized to make the right decision on that.

For delivery problems that don't result in a chargeback (the courier leaves it somewhere inconvenient, or claims you weren't in, etc, but it eventually gets to you) that's the situation where it becomes your problem and the merchant isn't much empowered or incentivized to fix it.