Smoothies can now be made easily and anytime at home but back in my high school days, the popular version was "shakes" usually made with tropical fruits. I remember a couple of flavors I would order, cantaloupe (melon) and sweet corn shake, made with canned sweet corn and evaporated milk. They were such a big hit that fruitshake stalls lined with electric blenders were everywhere. I've always been fond of icy fruit treats like these strawberry smoothies we often make at home (shown below).
I guess the popularity of icy treats will prevail. Then and now, cooling off is big business.