Modern washing machines auto-balance the load, which negates the need for the massive weights you get inside older washing machines for stability. The motors in older ones also have to work harder because of this since it is trying to spin an unbalanced drum. I also assume modern ones have more efficient brushless motors etc.
The load balancing thing definitely applies to the front loading washing machines we have here, no idea about top-loading.
I dunno man. That could lead to a gay arms race.