It certainly isn't unique to ecommerce. In the days when I was a bank clerk back in the 70s you used to meet all sorts. I ended up ordering one customer off the premises when he reduced one of the young girls to tears. I was terrified that he would complain to the manager and get me into trouble, actually he came back next day and apoligised.
Experienced a few in various fields over the years. As a magazine editor I recall the one who insisted that her ad should have priority despite having sold all available space because she had advertised before.