$135 is less than he would make seeing private patients, especially if it is more than a 15 minute visit (including documentation time).
Also, typically physicians need to bill an amount at least 3x their salary each year to cover the cost of office staff, office space/utilities, equipment & supplies, malpractice insurance, health insurance, insurance on equipment & office space, etc.
So, the doctor would have to go to 4 years of college, 4 years of medical school, & complete a residency (making around $50,000/year during residency) & possibly a fellowship at low pay as well & incur over $200,000 in education costs & then perform 9 CEs per day to make $97,000 a year.