"Automatic door—push to open."

This is the wording on signs I've been seeing quite often recently. It seems to me quite nonsensical; if you have to push the door to open it, it isn't automatic.

Is that the case or is there something about automatic I don't understand?

Solution 1:

Whenever I've seen this sign, it has been referring to a button on or near the door. Pressing the button causes the door to open automatically.

The buttons are usually placed to ensure they can easily be pressed by wheelchair users.

Solution 2:

I have that kind of door on my apparment building. Instead of having a separate button to open the door, the door itself has a sensor that notices when you start to open the door.

So, actually opening the door is not automatic, but then it will automatically swing open and stay open for a while.

You can compare this to other uses of automatic, where for example an automatic gun still needs a trigger, and an automatic gearbox needs to be put in drive.

Solution 3:

Automatic doors still have to be opened in the case of power outages, and having instructions for this contingency is a reasonable thing to do.