While in absolute theory, anything above 14/15 should give you the physical ability to drive well. Unfortunately, it's not the physical mechanics that are typically the problem. It's typically the mental restraint capability. Let's be frank here. For every Max, there's tens of thousands pretending to be Max that have a much higher probability of literally "crashing and burning."
Also, as to the liability, 100% accurate. Insurance companies are in the business of risk mitigation, not risk aggregation. There's a statistical reason for why we pay way more for our kids (16 - 25 no less!) to be added to our family car insurance policies. Heck, even car rentals places (outside of a few independents) won't rent to anyone under 25.
