I think you will find the almost 50% who do not pay taxes have been that way for many many many years. I doubt seriously anybody can find any credible source laying the blame at any one parties feet.

HOWEVER, what is the commentary about why democratic POTUS with a democratic controlled congress (that would be both the senate and the house) never did anything about it?

Most recently Obama's first two years in office with a democratic house and senate. Why no changes in this totally unfair method of taxation?

Because they ALL prefer re-election not fixing anything.

btk