Understanding the root of motivation

This may end up seeming like a rant about users but it’s not. I’m genuinely interested in what thought processes a $10/hr worker has, particularly when dealing with difficult, technical processes. I certainly don’t want to paint with a broad brush but there are a few that I just don’t understand. 

Is it a function of effort or ability? Surely there are other areas of their lives with additional emphasis? How do you best lead these folks toward further engagement? I’m at a loss.