You're a functioning adult with a reasonable intelligence. So why do you keep getting tripped up on a basic thing like opening a door? It's not just you. Some doors are designed to confuse you. As explainer site Vox points out, we subconsciously look for certain design cues on the doors we go through. You've probably never gotten confused and tried to pull open a door with a push plate or push bar. That's because the very design of these doors is obvious. However, other doors that try to emphasise style over function can end up confusing.
In design circles, these bad doors are known as "Norman doors", named for designer and author Don Norman. In his book The Design of Everyday Things, he explains that a well-designed door wouldn't need a sign to indicate how to open it. You would be able to tell just by looking at it how to open it.
Unfortunately, not all doors are designed well. For example, in office buildings you might find a glass door with a large vertical handle on both sides. A handle would suggest you might be able to pull it open, but on at least one side of doors like this, you can't. These handles probably exist to keep people's hands off the glass, or to adhere to a certain design aesthetic, but they come at the cost of user confusion. Signs can help, but if you and other people regularly get confused by certain doors, it's probably not you. It's just not a well-designed door.