> Accidentally losing a gun doesn't have the same impact that losing a phone or wallet has. ...

>Why would you ever treat a loaded weapon with the same triviality that one treats a wallet or keys?

A gun's very different than a wallet or keys, but we don't have separate brains for dealing with important things and trivial things. The same psychological limitations and afflictions apply to them all. There's a reason kids keep getting forgotten in backseats, and it's not because toddlers are trivial.