Doesn't that already happen? I've read stories from people in the US who are fooled, and as such, are marked as high risk and have their accounts closed. The rate it happens might be greater, but the total increase in harm from fewer people having bank accounts due to risk of scams might be less than the harm reduced by fewer people getting scammed. If scams are reduced enough, the number of people having bank accounts might go up because less people are losing them after being scammed.