> Of course, there is a reason for the separation of the closing and locking functions, but not the opening and unlocking functions: it avoids a Denial of Servi

> Of course, there is a reason for the separation of the closing and locking functions, but not the opening and unlocking functions: it avoids a Denial of Service attack where someone can just press “close” and then jump out before the door closes. If the interior “close” button automatically locked the door, this would result in the toilet becoming permanently inaccessible. There was a class of rolling stock used on UK lines (I encountered them over near Bradford IIRC) that had precisely that misdesign for the inside close button. I had to be really careful using those because my natural reflex is to hit 'close' on my way out for tidiness' sake, and I think I actually -did- the first time I used one of those and only realised what I'd done to my fellow commuters immediately after I heard the click.