The driver of real wages is the economic level of the whole country, which moves at a pretty slow pace (if at all) for an advanced economy. Many jobs today pay around the same as they did 30 years ago, because dollars (currency) aren't a measure of true value, and lots if not most jobs produce the same relative value today as they did 30 years ago.
To put that more plainly, lower class, middle class, and upper class defining jobs pretty much stay the same.
To put that more plainly, lower class, middle class, and upper class defining jobs pretty much stay the same.