The older ones usually make you wait for a minute or two before the door is unlocked. I have one in my current apartment that doesn’t do that, but I’ve tried it a couple times and it does spill some water when you open it.

With top-loaders, you don’t even have to pause, the lid is always open; and the water stays inside, obviously.

How do you do that without the water spilling out? Or do you mean waiting for it to drain, opening it, and then refilling (along with more detergent, having wasted the previous dose)?

Does the water know to stay inside the drum when you open the door?