I blame the teacher's unions and their resistance to change. I have never had an issue with math. My older son is not very good at it, however. My younger son may be much more proficient than I am. Why are they different?
A few reasons. First, my younger son loves sports and sports analysis. Statistics were something he followed from an early age. My older son did not. Secondly, my older son had different teachers and slightly different math programs. These programs mimicked the comedian's schtick:
The comedian Louis C.K. parodied his daughters’ homework in an appearance on “The Late Show With David Letterman”: “It’s like, Bill has three goldfish. He buys two more. How many dogs live in London?”
I had an extremely difficult time helping him learn his math based on the program offered by his school. I was unable to learn the principles they were making him learn, how could I provide any assistance?
My younger son's experience, on the other hand, engaged a teaching method similar to that mentioned in the first four paragraphs of the article. He was using life experience and discussion with friends to learn the basics. The math program he was taught was significantly different from his brother's, the methods similar to those I from which I learned (I know the way I learned math was different from public school kids - my Catholic school was outperforming other local schools on standardized tests for years).
Ultimately, it's important to realize math is the basis of logic and reason. A deficiency in math skills may go a long way to explaining why so many Americans think they can get something for nothing from the government. Common Core may have fine intentions, but its implementation is a disaster, and is heavily politicized. It is unlikely to solve the issues it is designed to fix.
The article carried this anecdote and seems to be a tremendous summary. This is the source of that anecdote.