Wow, complete consensus on BITOG. And I agree, "legal" and "not to the wear bars" is not the same as safe, especially in rain. I start shopping for tire deals at 5/32 and replace before 4/32 (typically). I would leave 2/32" wear to those in strictly hot, dry areas.
And dragging school bus regulations into this is a canard. I used to think lack of seat belts in busses was a crazy thing, too. Then I learned about compressible seat backs and compartmentalization. If you move a bus from the compartments strategy to seat belts, you have to replace all the seats with non-compressible seat backs. The result is LESS safe in side collisions. It is also LESS safe for the odd kid who failed to buckle up, because they're now hitting a hard seat, not a compressible one. You also add a burden of seat belt use compliance to the driver.