Brake Master Cylinder problems of the 2012 Chevrolet Express

I manage a fleet of 53 school buses, model years ranging from 2008 to 2015. I have noticed a trend with the hydro boosters and master cylinders, they tend to leak internally on these gm vehicles some have begun to leak as early as 30,000 miles. I expect to have to replace all of these components, on every bus in the near future. As the fleet ages the trend is getting increasingly worse. I believe this is a dangerous situation because I am vigilant with keeping up on this issue, however I am not sure that the general public will have the same understanding about the danger of this design flaw. I have had buses come in bleeding brake fluid or hydraulic fluid.