Many people “sample” books at the bookstore, see something they like, pull out their smartphone and order it from Amazon right then and there.
Before smartphones, they used to have to go home and order it from their home computer. Nowadays people can just scan the barcode and order it from the cheapest retailer right from their phone. At least I think they can do this. I just might be the last American without a smartphone (and I'll probably break down and get one sometime this year).