Gustavo, it is more complicated than you would like.
This reputable source tells you that roughly we spend per capita twice as much as average of comparable developed countries, https://www.healthsystemtracker.org/chart-collection/health-spending-u-s-compare-countries/#item-start.
When you Google “waste in healthcare” you can find plenty of reports, most of them agreeing that about one third of money spent is wasted.
When you ask why, things get complicated. People advocating for a socialized health care system would say that we have too much greed and too little oversight. This is a point of view of Cheney, the author of the original text, and Marc Michel responding to my post. By the way, this was as well the position of President Obama and his team, when implementing Obamacare.
I have a fundamental disagreement with this approach, because all what I know, makes me doubt that we ever would be able to construct a bureaucratic system outsmarting ingenuity of people trying to find out the best way to satisfy their personal needs. My understanding is that we need a system recognizing these inner human desires, not a system trying to stifle basic human instincts in the name of an abstractive lofty good of the society as a whole. A lofty good abstractedly defined by self-anointed sages.
Returning to your original question, the waste is clearly documented. Finding the reason for it and how to fix it requires you to do your homework in understanding how things work, and make you own conclusions. If you are interested in finding more about my take on it, please check my texts here; and, ask questions.