I spoke with my Dr. about why they still do such an invasive procedure that is potentially dangerous.
At the time I had been for a CT Scan for something else. They didn't find anything

and he was also able to tell me that there were no blockages in my arteries as an aside.
I asked why they don't do that instead of a colonoscopy since it's able to pickup such small details.
Answer was that during a colonoscopy if there are polyps they can get an immediate sample.
I asked how many have polyps. Not many.
So the large (vast) majority of us are forced to undergo an uncomfortable, potentially dangerous procedure that could be done much more easily. For the small number that do have polyps etc this could be followed up by a colonoscopy.
I'm convinced Drs. make more money the invasive way.