Top loaders are still common in Australia and New Zealand. They’re terrible, but they are cheaper than front loaders and are what many people are used to.
I can pause my front loader and add laundry, I'm not sure how the machine does it, perhaps I cannot add just whenever I want -- depending on the wash cycle, but I've never had the problem of not being able to pause the washing and add new laundry that I forgot.
Front loaders are extremely water efficient, there’s not much water in there and when you use the pause feature it can drain away enough water should that be necessary to make it safe to open, but mainly it just gives the clothes and liquid a chance to tumble to the bottom as they’d all spill right out otherwise and (then release the lock to make actually opening the door possible). By contrast, top loaders don’t even have a lock and don’t need a pause feature. There is usually a trigger switch to detect when the lid is open to stop the agitation for safety reasons, but there is no mechanical lockout and no delay: you can just open the lid.
