Yeah I usually have to request blood work.
I'm pretty sure 99% of the US is healthy, but almost all of us think we are sick and dying from one thing or another. Doctors are the only ones who realize that almost everyone is healthy. If you are young, as long as you look relatively healthy and not morbidly obese and don't have a specific identifiable symptom that youre suffering, then doctors aren't going to bother with you. Even if you are in that rare 1% and are sick, more than likely a doctor isn't going to catch it anyway unless you have those identifiable symptoms to share with them.
A doctor can't just listen to your heart, check your ears, take your blood pressure, and then diagnose you with Crohn's disease.