I have also encountered web forms which must validate my address. Turns out, the backing database did not contain my address. I could not order at the store. After contacting the store, they told me that their data was always accurate and therefore I must be a fraud.
The first time I ordered something from Amazon to be delivered to my workplace, I spent like half an hour trying different variations of the address so that it would pass the validation. And my workplace is a university building where 200+ people work, in a European country. Finally, I got it to work by typing "Campus of Place, Faculty of Building". It wouldn't work without the words "Place" and "Building", which we…
Probably because it doesn't Just Work(tm) as well as you think. People in general are pretty bad at knowing their actual deliverable address - if you are someone as large as Amazon having even .1% of your packages returned due to user input address errors is likely quite a lot of money.
Having briefly done e-commerce stuff where we had to ship low value product en-masse I tend to think that .1% is a low estimate - but maybe people have gotten better at this since the early 00's.