So i should?

So a few months back I decided to go get a haircut. Long story shirt, I got one, and as i casually walked through the crowd of unfriendly faces that is Brighton Beach, i walked up the stairs to get on my beloved Q train. But what do i see when i approach the door i want to use to get upstairs? This: Now i don't expect the people who work at this train station to be the most intelligent bunch, but you certainly don't need to be th next Albert Einstein to know when to use quotations. When i saw this sign, all i could think about was why...why in the world someone felt it was necessary to put "do not" in quotations...are they simply implying that I should use the door? or was that their way of emphasizing the fact that i shouldn't, as if the presence of the double underline didn't tip me off.