If you insist on keeping kids on buses for an artificially long time, you're insisting on creating more trouble on buses.
If you insist on spending a lot more money for busing to reach social goals, then you will have less money to pay bus drivers-- and more importantly, for education.
Econ201: We know how shortages arise and persist-- in labor markets, when compensation is inadequate. This ain't brain surgery: Pay them more and watch the shortage dissipate. (See also: labor union opposition to market wages for science, math, and special ed teachers.)
Related to this, Hargens notes that it's more difficult to find bus drivers (presumably at, more or less, the same wages) when the economy is stronger and labor demand is higher. All labor demanders must pay more in this setting or face shortages.
It's annoying and perhaps telling that Hargens uses the word "again", again and again, in the interview.
Hargens repeatedly refers to the proportion of incidents-- and of course, that's the best single approach. That said, I hope that she and apologists for JCPS do the same thing in other contexts-- e.g., focusing on the ROI of large companies rather than their profits.