Doctors are educated to do more and now they have to do less...

http://www.nytimes.com/2012/06/05/health/views/essay-urging-doctors-to-do-less-may-fall-on-deaf-ears.html?_r=1&nl=health&emc=healthupdateema2_20120605

Screening is a very speculative medicine because it is about treating patients who are in good health... Indeed it could be difficult to chose between the risk of the natural history of the disease and the risks of the treatment.
It's so true that money is not the main incentive. It's a mix between education and defense against litigation. A mix which is very hard to fight when studies show that doctors have to do less.