To send you tax information, mostly. This is a stupid thing to be mad about.

Just put their office address in. If they query, just say "Yes, I'm already living there so you may as well give me a job while I'm there".

So they can mail you things? I understand that most things can and are done digitally, it's still very common to mail things to prospective employees. Contracts hiring them, for instance.

Or, in your case, if they're a classy employer, a letter denying your application.

Isn't your (and everyone else's) address public information anyways in your country?

Here you can search for whoever and find their full name, address, and a bunch for information. If you pay a small sum to a company (or call the tax agency yourself for free, but that's annoying) you can also find out how much money someone is earning.

Almost every phone number is also available and searchable online.

All this information is also available if you for example know the car plate number of someone's car.

They may be checking to see which candidates live in a "hub zone" for certain credits through the SBA if you're in the US.

Answer: taxes, actually. If you become an employee, your actual address is needed to ensure taxes are taken appropriately. This is true especially in work from home situations.

Background check?