Public Washrooms are mine enemy

Here it is... a blog dedicated to the one public bathroom that creates the most rants in my life. My bathroom at work.
Alright so TECHNICALLY I have a bathroom in the office here... but its creepy and wrong and who knows if or when ANYONE ever cleans it... plus the seat is cracked, the floor is gross (and carpet may I ad) there is hardly any light and people can hear EVERYTHING you do in that bathroom if they are anywhere in this office space. EW!. no. Thank you.
SOOO I choose to venture to the main women's public bathroom on my floor. You need a key to access this washroom and it is a one toilet room, a rather large room actually.
My problem comes in with the whole "keyed" bathroom thing. I do not understand how people just go about life completely unaware of the fact that perhaps there are OTHER people who also have to use the bathroom. I have many examples of this. Mostly out of annoyance, I actually remember them. I can't count the MANY times I've gone to use this bathroom and actually walked in on someone IN the bathroom. This befuddles me each time as there are TWO locks on this door... the one on the bottom unlocks with a key, but the deadbolt on the top turns the OUTSIDE screen to "DO NOT DISTURB" in red letters. Kinda hard to miss unless you are an idiot and there are apparently MANY of those. How do people not bother to lock the door on a public washroom. There are 20+ Dr.'s on this floor... so I'd assume at any given time there are at least 25 people here to see Dr.'s... of these 25 people do you not assume that someone MAY also have to pee at the same time as you. Or worse... leave the GI Dr.'s office and have to suddenly evacuate or something. Why would you not lock the door?
SECONDLY... why would you walk up to said public bathroom and NOT notice the bright RED letters saying do not disturb and at such point where you use the key and it does not in fact open the door (despite turning the handle)... why must you persist in trying to RAM the door open? Are you not aware that perhaps it may be locked? Perhaps someone is already using it? Perhaps you are not the only person on this floor at that particular time that has to pee?
But really... if the door does not open on your first 6 attempts, why do you continue to jiggle handles and push knobs and repeatedly try keys... before attempting to battle ram the door itself with your entire body. At this point, I'd seriously consider making a habit of going to the bathroom before you get to the point where this type of behaviour becomes a necessity. Agh.