Software/Web Development Is Not Software Engineering
googleyasheck.com
googleyasheck.com
Very little software (even at Google/Apple/Facebook/etc.) is written to that standard -- regardless of how many "Software Engineers" they may employ -- because the cost of mistakes is still far less than the cost of adopting a more formal approach.
It's all about the process. Answering algorithms questions off the top of your head is neither here nor there.
Anyone who knows an engineer will certainly have a story where he sets off to perform some trade around the house with a "No sweat, I'm an engineer!" attitude, then nearly burns the house down.