In reality, the fact is that seeing someone's face means almost nothing unless you literally know the person, and even then, it's not a guarantee. "Everybody looks like somebody" applies. If someone saw Clark Kent without his glasses, they wouldn't say "OH MY GOSH IT'S SUPERMAN;" they'd probably say, "Hey, mister, without your glasses on, you sort of look like Superman. That's kinda funny."
The Spider-Man films have dealt with this repeatedly. Sure, people like Mary Jane and Norman Osborn would recognize him under the mask, but dozens of average New Yorkers see him unmasked and don't know anything about who he is other than "he's an average-height white guy with brown hair."
The only people in horrible danger of being recognized would be celebrities, like Oliver Queen and Bruce Wayne. However, even they have the "everybody looks like somebody" rule to protect them to an extent. And since they both largely stick to the shadows, darkness can help cloak them.
So, before you cry foul at Clark losing his glasses or Spider-Man pulling off his mask AGAIN, remember this and calm yourself.