Then why was the age arbitrarily set at 26 for coverage under parents plans? Why not 30, if the goal is to increase to pool of healthy people?
Most people by 26 are working and covered by their employers plans. People 18-26 are more likely to be either unemployed or in college without a healthcare plan.
I suspect it was because they wanted to set the age at a point where college graduates would be included in the insurance pools even if they wanted to go to graduate school before they got their first “real” jobs.