On the right, they don't want to believe that it's anything other than a matter of laziness and addiction to welfare. On the left, they don't want to confront the subcultures that reject the values that make you successful and embrace behaviors that make you virtually unemployable.
Nevermind the issue of what you do with millions of people on the low end of the IQ scale in an economy that increasingly requires complex and abstract thinking to perform the jobs that pay anything. Not to mention the vanishing of low-end, low-skill jobs that are replaced by machines or are done by a smaller number more intelligent people who are underemployed.