>4. If Fulfilled, now I have to research how reputable the selling company is. Just yesterday I found a company selling baby formula, whose domain name was registered last month, and via a privacy service!?!!? If you can't list your business address, I'm not buying from you.

Come on, basically every registrar forces private registrations on by default now.

It's very easy to lie in whois data, those that want to conceal their identities will just lie instead of using a proxy service.