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?
I got a side loader and it generally is spinning at least a little slowly until right before the timer goes off. Generally I can push the pause button at any point during the wash and after a few seconds it will unlock. My top loaders i used to be able to open at any time during the wash.
I imagine they have a buffer period to let the load stop spinning but you probably can override for earlier if you really want.