From my experience, only some Carnival and Princess ships have self-serve laundries. I don't go on cruises to do laundry, so I really wouldn't know the specifics for all lines.
I know one thing - I will never book a Carnival cruise where my cabin is right across from the laundry again. On the Legend we were in this situation. I don't wish to sound snobbish, but some passengers showed up there (they apparently were cruising together) and spent the day and evening there! The women were doing everyone's laundry from the group - including ironing, the men had pulled chairs from other areas of the ship and were sitting in the passageway. They would take turns going to a bar to bring back beer. This started at mid-afternoon and they were still there at 8pm. Very strange. I think enough complaints were made and some officer finally broke it up.
I think it is a good thing that RCI has no "launder-coin" operations!