In the past, a single house hold earner could provide for a family. Now it takes two.
What's changed? THAT'S what we need to look at.
I suspect it will be a mix of increased costs due to:
Government regulations and their impact on manufacturers.
Industry practices...required because they can. fees surcharges, penalties, etc.
Increased consumer materialism. You HAVE to have the big screen TV, you HAVE to have that 4 wheeler, new car, etc.
You're mostly wrong - since the 1970's, inflation has increased at a steady rate, but wages haven't kept up; in fact, real wages have been decreasing over the past few years, while inflation has continued to grow.
So the question you should be asking is, "Why haven't wages grown along with inflation?" and the simple answer can be found in the CEO wage gap and greedy shareholders only concerned about short-term financial gain for themselves, consequences be damned.