That's pretty understandable. If you already know that it bugs them (probably a lot if they have this much of an issue with it), and yet you keep doing it, they probably think you're doing it on purpose.

Where do you work? In this case, it definitely matters if you're in a cube in accounting, as opposed to an Antarctic research station, supermax prison, or disease lab.

Have they warned you before? Leaving a door unlocked could have some serious consequences depending on what industry you are in OP.

So don't be so rude, OP! Click the door properly shut when you leave. Very simple to do.

Not clicking it properly means you haven't locked up at all, & the entire place is at risk to thieves.

To be fair, I'll be unhappy if one of my colleagues doesn't properly shut the door on their way out. This means that one of us needs to be interrupted from our work, get up and do a job any 5 year old ought to be able to do without being reminded repeatedly.

Learn to click the door shut and the problem will go away.

Learn to close the damned door, it isn't really all that hard.

I get the feeling you're leaving out pertinent information.