[chinstorff]

> if it fails, the failure is contained

What about the failure mode when the courier doesn't follow your parents instructions and leaves the package on the porch?

Now you have the code to the lockbox of the key to the house sitting on the porch where anyone who approaches can gain access to the house.

[ajoy39]

The lockbox was for the packages themselves, not for the keys to the house.

[crescentfresh]

Oh boy, took your comment to finally get this. I take lockbox to mean the thing you put on the front door itself to gain access to the house.

[eric_h]

It means that, too - real estate agents use the term for the little key box they use to let other agents see vacant houses.

Personally I'd use the term "locker" to refer to a box placed outside in which to store packages.

[bagels]

You change the code, and a few packages get stolen just as would happen if you didn't have the box.

[em3rgent0rdr]

Don't put your house key inside the lockbox!