I hate to say that's it's too expensive for the school system, but that's probably why.

Im 13 and i ride a School bus to & from home every day for 3 yrs and(this is all the same driver causethey dont hav enough bus drivers) in that three yrs the bus has:
Caught on fire
Ran in to a car
hit another car i live in memphis
hit a stop sighn
was hit in the back cause my bus driver ran a red light one after noon
Almost fliped cause She ran another red light

on all of those excpt fire having seat belts would hav been nice!
But SCS schools cant afor them

Compartmentalization, a concept seen frequently on commercial airplanes, involves seating passengers in rows of padded seats with cushioned backs.

The belief is that during frontal or rear impact, the most common types of wrecks involving school buses, passengers would either be pushed back into their seats or thrown forward into the padded backs of the row ahead.

The use of seat belts might require stiffer seats, which would negate the theory of compartmentalization. It is also feared that some students would receive internal injuries from seat belts through a process called submarining, the tendency for a body to slide downwards during impact.

Seat belts on school buses may also hamper rescue or evacuation efforts, as adults or older students may have to spend precious minutes unbuckling young or disoriented passengers.

Unruly students could also use the heavy buckles as makeshift weapons, creating even more of a safety hazard.

There is also the argument that seat belts would only protect passengers of school buses during unusual events such as roll-overs or flips, not other possible accidents such as fires or submersion.

Considering the expense of retrofitting current school buses or replacing entire fleets with approved seat belt systems, the benefits of seat belt use do not currently outweigh the liabilities.

School Buses are designed with high back seats that are heavily padded. So if the bus is in an accident the passengers will hit the seat and cause little damage to the passengers. Not only that the district would have to hire bus aides to make sure that they stay in them at all times and be ready to cut the seat belts in the case of a roll over and this means more state funding. On the large buses 72 passenger buses your looking at a minimum of 3 aides. But believe it or not the passengers will use them for weapons (hitting one another with them.).