What if the kid had been running? She wasn't going real fast on her bike. The car however was well over a safe speed for a parking lot (10mph) and quadruple the speed that is reasonable for a school parking lot (5mph) as there are very likely to be kids at any time. Car driver is 100% liable as she was operating at unsafe speed and possibly trespassing(why do people in cars think they can cut through parking lots) and was not exercising any due care, she was either looking at her phone or inebriated, or it was intentional.
. I ask about running because a child run over in a school parking lot by some jerk who wasn't supposed to be there , without a bike involved, would have most parents groups wanting the woman's head.