Author thinks he needs the ZIP code database that is "updated daily," but he provides no reason for this and he's not willing to pay for it. Looks like he's the one being unreasonable here; ZIP codes are a solved problem.
Why should he pay for something that is a product of the federal government? It's already paid for, by the salaries of those who maintain the data, which would be maintained anyway since its required for USPS operations.
Presumably those salaries were paid with the expectation that some of that money would be recuperated through private sales. I guess it sort of makes sense that only businesses who use the information have to pay, instead of making every taxpayer bear the burden.
Taxpayers don't bear the burden. Postage purchasers do. If you paid for postage, the zipcode database was necessary for delivery of your item. Selling the data to other companies is just another way they're trying to monetize the data.
The USPS is not a government agency nor are its employees paid by the government.
Even more unreasonable: His original reason for wanting the list of zipcodes was to correlate the zip codes of some health inspections in some county in Oregon to a specific location. Undoubtedly, these health inspections are older than one day, and therefore using two year old data from the census would probably provide the same accuracy as the zipcodes updated daily.