Don't these private carriers already share address databases, or outsource address lookup to third parties with incentives to find the right location for any valid address? Adding a level of indirection to that existing system wouldn't take very much effort.

Or do you have one address for UPS deliveries and a different address for FedEx deliveries? (Substitute local carrier names as appropriate.) While that's more work—and pointlessly complex IMHO—you'd just need to set up one ID per carrier and give the correct ID, as opposed to the carrier-specific address.

I don't think they share any information, or maintain address-databases. Usually there are official geodata (maps, postal codes) and customers normally don't report back their own data to the government. Anyway, logistic of postal sercice is highly optimized and well defined, and changing anything is not as simple as hacking some script somewhere.

If they can't easily implement something as simple as a mapping from IDs to addresses, that seems less like "highly optimized and well defined" and more like "inflexible, cobbled-together mess". I don't doubt that what they're doing works well for the situations they've encountered in the past, but situations change and they need to be able to adapt.

Anyway, a shortcut to implementing indirection for these less-organized postal services you're describing would be to look up the recipient's ID when the parcel first enters the system and affix a label with the full address. That way the sender doesn't need to know the address and everything else about the delivery can stay the same.

Highly optimized and well defined solutions are by definition inflexible. Because they are the result of removing everthing which is not relevant for the task. If you are a company handling thousand of letters per minute, then you don't have any reason to be flexible, because the task does not change between the iterations. I mean we are talking here about industrial level of optimization, not some dude in his small office stamping his three letters a day. Companies on such level optimize everything from highest to lowest levels, because any optimization can make a difference of millions of whatever currency they use.

In that scale, nothing is simple, because everything can become expensive on the high run.

> Highly optimized and well defined solutions are by definition inflexible. Because they are the result of removing everthing which is not relevant for the task.

Only if you don't consider flexibility part of the task, which is rather short-sighted in today's world. Maybe postal services could afford to be inflexible once, but those days are long past.