Because some parents are pretty clueless about what makes safe (or for that matter, unsafe) racing conditions. The kart track at PBIR is pretty intense- and probably too much for the skills of most 9 year olds.
Sad to hear about anyone being injured, especially a kid (mine races Jrs). But you're right- at some point there was a lawyer in a hospital lounge discussing the "negilgence" of PBIR with the greiving parents. Where the track may be in trouble is if there was a tech inspection issue that slipped through- note the report also said they were suing the kart motor company. Maybe the motor hung open, causing the kid to lose control? And the tech guys missed something like a return spring that should have been on or a functioning kill switch?
I'm interested in the recovery of the kid and where this case ends up gong. Wishing everyone the best recovery....