I have a front loading washing machine and it is on the floor.
DS climbs into it to pull the clothes out if it isn't clicked closed properly. He can also push the start button (partly cos I taught him!)
The dryer is hung up above the washer, so no way to get into that.

He climbs into the dishwasher too if the door isn't fully clicked shut.

I have heard of cats being put into washers and dryers, as well as siblings. Maybe the only answer is a good lock on the laundry.