I extracted the following paragraph from the book "Why Employees Don't Do What They're Supposed To Do And What To Do About It (By Ferdinard F. Fournies)".
From my personal perspective, if there's one most important take-home point from this book, this is it.
According to human behaviour research, the weekly paycheck does not qualify as a reward that influences people's productivity. The psychologist B. F. Skinner once observed, "People don't come to work to get paid, they come to work so the pay doesn't stop." Additionally, in most business organizations, an employee can perform badly for a long period of time before the pay stops. Getting a weekly pay-check is like breathing; it only becomes important when it stops.
So in summary, nobody is going to be motivated to do better with just wages alone, regardless the quantum. It's also similarly unrealistic to suggest that an employee is supposed to be doing something because he is paid to do them. This is because what you think he should be doing may not necessarily be the same as what he (really) thinks he should be doing.