Are American kids actually delaying adulthood, or is the metric broken?

Standard claim: kids today (18-25) delay marriage, kids, home buying, etc. relative to prior generations. The numbers do show this. But marriage and homeownership are *outcomes* dependent on relative cost and labor market structure. Median age at first marriage being 30 instead of 24 might just mean houses cost 4x more, not that the same human is "less adult." A better test would be psychological/behavioral indicators of adulthood — financial planning horizon, willingness to commit to long-term obligations, willingness to make irreversible decisions. Are those actually different? Has anyone looked?