Most washing machines have a timer that prevents you from opening the hatch just after the washing cycle ends. Instad you must wait for the timer to go off, usually a minute or two, before you can open the hatch.
Why? Would letting the user open the hatch immediately after washing ends pose any safety or other issues?
My best guess is safety, if you had a heavy load in there the momentum could keep the drum spinning much longer than normal. I’m sure they could add a sensor to check, but that’s just an extra cost. So rather than allowing you to open the machine while it’s still spinning and possibly injure yourself reaching in, they keep it locked for a few more minutes.