Well then I haven't been wasting my money all these years
I personally always wonderd why it has/needs a hechsher. It is possible that
dishwasher detergent is more complex than dishwashing soap because dishwasher is possibly a kli rishon with heat etc.
I can tell you that this
is mentioned in Shulchan'O/ nosei kelim: soap in olden days made with fats etc... dont remember where or what the bottom line is... Ask a LOR if there is reason to be
Machmir (IIRC nosen taam lifgam is ossur to do lechatchila?)