How do general contractors ensure that they are paid on state projects in Wisconsin if they can't make a bond claim?

We're working directly with a school - is there any way that we can ensure we get paid. It sounds like only subs can submit claims against the GC's bond. So do we need to take out insurance (or a bond) on our own project. What incentive is there for the school to pay us in that case? It seems like a loophole for them.