A lot of very large, very public websites have very poor procedures for handling being contacted from the public.
Some times there may be a contact e-mail, but you have to stumble onto it, like after hitting a 500 error page (though often error message contact info is hidden, too).
Other times the e-mail is some internal address that's used for testing, or is non-routable, and the mail goes nowhere. What server is it forwarded to from the public-facing MDA? What mailbox? Is it an alias? A group list? An individual?
Other times, maybe somebody gets the mail, but nobody knows what to do with it. Who checks it? Who figures out where it needs to go? Who replies to it? How do you know if somebody never follows up on it, so that you can re-try to get a reply from someone internal? Does the e-mail seem important enough to even warrant a reply (does anyone care)?
And a lot of the time, even if there's a contact page for the whole site/company, there's no e-mail address, because nobody ever planned for there to be a generic contact e-mail for the whole site or company. How do you reply on behalf of all of Microsoft? Of General Electric? Of Kraft?
Almost always, if a reply does come, it's because someone went above and beyond their normal job duties just to make sure you, the inquiring party, get your question answered.