I'm sure everyone has experienced double doors at the front of a business in which one of the two doors is locked. A relative of mine used to be the director of franchising of a restaurant chain and he noticed that literally hundreds of people would try to open the wrong side of the door every day in every restaurant where this happened. When he asked store managers or the employees about this, he would get evasive or invented answers: it keeps the heat in on cold days (or keeps heat out in air-conditioned locations) or that the second door wasn't working.

Hardly anyone wanted to admit the real reason, which turned out to be as silly as you can imagine. The first employee of the morning that came to open up the restaurant opened one side of the double door. Flipping up the hasp that frees the second door is a bit of a chore, so he or she wouldn't bother. And nobody else bothered as well.

The head office had to put a requirement in the operations manual that franchisees must unlock both sides of the double door when the restaurant is open for business. That mostly solved it.

EDIT: Of course a better solution would be a mechanical mechanism that frees both sides of the door simultaneously when you unlock it.