And keeping such datasets up to date is another matter entirely, because clearly a lot of companies rely datasets that were outdated before their company even e

And keeping such datasets up to date is another matter entirely, because clearly a lot of companies rely datasets that were outdated before their company even existed. A trivially simple example of just how messy this is when people try to constrain it is that it's nearly random whether or not a given carrier would insist on me giving an incorrect address for my previous place, seemingly because traditionally and prior to 1965 the address was in Surrey, England. The "postcode area name" for my old house is Croydon, and Croydon has legally been in London since 1965, and was allocated it's own postcode area in 1966. "Surrey" hasn't been correct for addresses in Croydon since then. But at least one delivery company insisted my old address was invalid unless I changed the town/postcode area to "Surrey", and refused to even attempt a delivery. Never mind they had my house number and postcode, which was sufficient to uniquely identify my house.