The seatbelt analogy is pretty good actually. A seatbelt system costs several hundred dollars, surely. What's a 12-lead ECG test cost? It can't be THAT much seeing as italy does it on every kid who wants to do sports. Lots of rich private schools in the US do it too.
More derp. You can't diagnose very much with an EKG unless you're quite literally about to drop dead.
At minimum to diagnose hypertrophic cardiomyopathy, you need to do a echocardiogram. Not cheap. In addition, a stress test would be needed. Perhaps a holter monitor and several other diagnostic procedures.
The school district shouldn't be spending other people's money. If you have a concern about your kid, talk to the pediatrician.