I shouldn't have to accept government surveillance just because 15% of the population is functionally illiterate. We should have support structures for those people as a society, but "dumb people exist" is a fucking horrible argument for why I should have my freedom restricted
There doesn't need to be a solution that works for everyone. It doesn't matter how many barriers you put in place, people will always get scammed - so don't punish the other capable 85%.
You do in fact need a system that works for the vast majority. If your system flat out doesnt work for 15% of the population, you'd have mass riots and unrest.