The real problems are 1) that the high school curriculum still assumes that students have the sort of intuition about arithmetic that is built up by doing problems by hand, when in fact they have used calculators, and 2) that most K-8 teachers are math-phobic.
To address the first, either calculators need to be forbidden until the courses normatively taught to college-bound high school juniors, or the curriculum from the early grades on needs to teach in a more thoroughgoing way what is really going on when you use a calculator and how to do estimates mentally so you can tell if you’re getting rot from your calculator because you pushed a few wrong buttons, then exploit the ease of calculator use to give more extensive work both applied and theoretical as a way of building up mathematical intuition.
I teach mathematics at a large midwestern state university, and I don’t really care which of those alternatives is pursued.
To address the second, I’m afraid the several states need to revoke the monopoly on teacher certification given to Colleges of Education. That’s where the rot in American education is at it’s worst, not (suprisingly) in the teachers’ unions, bad though they are.
The "real" problem is that [almost] 50% of the kids these days are coming from groups which are at least a standard deviation stupider than the groups we were familiar with when we grew up.
And there's not a damned thing anyone can do about it - well, except for smart people to start making babies again.
But until smart people start making more babies than stupid people [and I know of almost no demographic data anywhere which would indicate that that is happening], the world is pretty much doomed.
Prepare for the worst, because it's coming.