For me, the difference is that with congestion charges, there is typically another way to achieve the same end - alternative transport methods, or routes which

For me, the difference is that with congestion charges, there is typically another way to achieve the same end - alternative transport methods, or routes which avoid the area in question. I think that's not necessarily true with schooling - even just having to travel further because the nearest school is chargeable may have an impact. I also think that there are reasons to avoid it with schooling even if the educational outcomes are the same -- I think separating schools into "can/will pay" and "can't/won't pay" would be bad for social integration/cohesion. Further, a congestion charge applied to road usage is probably, partially, intended to discourage use altogether. That clearly isn't the case for schools.