They mention car accidents as a statistic that drops off after the age of 25 (I only briefly skimmed the article).

I have thought for a long time: leave it to the insurance companies/number crunchers to best predict when "maturity" sets in (at least for the average young adult). The fact that you can't rent cars until the age 25 always suggested to me that the insurance companies had run the numbers and pin pointed this age as when it is "safe" to trust someone with their assets.

When there are legitimate business interests at stake (read: $$$$) they tend to get this stuff right.