There is no reason at all - no one is "requiring" doctors to do anything at all. However, the invisible hand of the market do provides incentives for doctors wi

There is no reason at all - no one is "requiring" doctors to do anything at all. However, the invisible hand of the market do provides incentives for doctors willing to do that job! The reason is the difference in financial gain if for some reason (domain knowledge) a doctor can perform the same job more efficiently - which is usually the case in medical coding, where a doctor usually know better which complications are linked with which diseases, and which procedures must have been performed and thus, if they don't appear, have usually been done but for some reason the coding didn't happen. That's just 2 quick examples - a physician can "dig" in the file for supporting evidence to back the claim. Some are quite good at it, and with the numbers at hand, tiny differences in productivity make huge financial gains. Say that worker 1, anyone with good training, can make 2x returns, while worker 2, a doctor, can make 2.2x returns. Depending on the volume, you hire both and give the common files to worker 1, and big profile cases to worker 2. Each worker is usually paid at the marginal value of labor. When the marginal value of billing improvements become greater than the marginal value of clinical care, labor do arbitrage and moves to the higher paying sector - in this case, doctors are going for clinical practice to billing. Someone with basic training - or even algorithm - can be efficient, and provide a first line of coding. But domain knowledge still rules and brings in big bucks. Trust me - my job is to bill patients/insurance as much as we are legally allowed to, using any mean necessary, in a way that will stand in court if challenged. We're long past data-mining for potential missing codes - we now run simulations to isolate which coding is the most probable and the most lucrative, and divert the file to the right person according to the potential financial gains. Any loophole in the coding rules is exploited big time ! A quick example - several years ago there was no consequence if you "forgot" codes, however simulations figured out in 10% of the case this resulted in greater gains. Consequently, after a matching legal advice, codes were forgotten 10% of the time - of course, the right times, until forgetting code was disincentivized thought legal changes.