Professional courtesy is not obsolete in my practice. It is a token of respect for a colleague or allied professional that has spent countless hours away from his or her family to ease the suffering of others. But I do agree with the author that it will be obsolete.
Extending professional courtesy usually means waiving copayments. Medicare can fine physicians for fraud because they assume the the total fee is inflated to compensate for lack of copayment. An analogy can be make with an auto body shop that waives a deductible. The auto insurance company will certainly investigate. Years ago, I made house calls in a local convent. I was treated with the respect usually given to priests as they were gratefull for my visit. I had to demonstrate a reasonable effort to bill the convent even though I felt my visits were a courtesy.
Also, these days clinicians are increasingly removed from billing practices. Most just want to document what was done and leave the billing to others. "Just take the ticket and bring it to the cash register" will be the prevailing sentiment. No room to wiggle there. Maybe rightfully so.