I have no good idea about the origin of users as lazy. However, there is a good argument for an origin of users as stupid. And this might be the close connection of Human Computer Interaction with Cognitive Science, which understands thinking as computational. Thus, the ideal way of thinking is computer-like and diversions from this are framed as due to limitations that cause problems and need to be worked around: The user is like a limited and erratically failing computer.

Gedenryd showed the problems of understanding the user and designer as thinking computationally in his PhD thesis: https://www.semanticscholar.org/paper/How-designers-work-mak...