If your evidence is only anecdotal then I think you need to go find some better evidence or go back and rethink your argument. Calling voucher systems a "scam" based on this reasoning is a big stretch. There are lots of other ways for "low cost" students to accumulate interactions with "high cost" students that don't require them to all be educated in the same manner e.g. out of school activity clubs, local community groups, religious organizations, boy/girl scouts. Why not give students a say in how they are educated and make those opportunities more accessible / subsidised?