A Doctor is a doctor. A Controlled substance stays the same if you are in Kansas or Colorado. That's already decided at the Federal level. A patient remains the same regardless. Many doctors travel across state lines especially in rural areas. It's not just sports teams. And it's not just opiates. In a natural disaster, a terrorist attack, a roadside emergency, anaphylactic shock on the beach or in a restaurant where they swore there were no nuts, it would be prudent and miraculous to have a doctor at the scene with limited meds to assist. I know if I were having a heart attack in a restaurant and a doctor on vacation were there, I'd like him to be able to do something besides dial 911 and chest compressions while we all wait for the ambulance.