I think another major reason powerlifting is more well known and gets more participation in the USA is because you can pretty much train for it in the average street gyms while these gyms won't allow you to do the Olympic lifts- at least won't tolerate platforms, dropping weights, etc. This also increases Americans exposure to powerlifting while Americans rarely ever even see weightlifting.
But i believe that powerlifting is big here for one reason is football. football players do a lot of the training that i believe is crappy which is similar to powerlifting. americans like seeing big numbers and brute force. same reason why americans like football instead of a more complex sport like soccer. they want to see big guys doing big things. and the numbers just dont excite people like in powerlifting
"Are powerlifters athletes?" & "Are weightlifters athletes?"