As for Bill Gates, I haven't really been following but he's the largest back of charter schools in the US, teaming up with the Walton family, and likely working with DeVos (I haven't checked).
Charter schools could be useful if limited and handled well, but usually they are just used as a means of making a profit, harming public schools, undermining teacher unions and skimming off the best and most motivated students (and thus harming public schools).