[sethg]

they've apparently deliberately designated a large number of shipment delivery locations as residential delivery

More likely: they have a database or some other kind of service that maps addresses onto “residential” or “not residential”, and either they put off upgrading the database or have some flakiness in their code, so that a lot of addresses get incorrectly marked “residential”, and, well, when you’re prioritizing which bugs you need to fix, the bugs that make your company more money than it deserves usually don’t end up at the top of the list.