Technology

One answer could be that the organization maintains a large fund to act as a buffer to maintain salaries between contracts instead of operating “paycheck-to-paycheck.”

Thats great in concept, but keep in mind they're already taking customers that likely have small or limited budgets. Where does this extra buffer come from? The only income stream is delivering on limited contracts to cash strapped NGOs and non-profits. Remember, they took corporate work at one point, but hated it. Corporate work is where the bigger bill rates for delivery of contract service come from.

An even simpler answer could be that the co-op chooses to take on a large number of small contracts instead of a small number of large ones, such that the revenue is relatively consistent to begin with.

Its amazing if your org can get so much contract work that there's jobs available to turn down. This usually requires a dedicated sales and marketing staff, which don't generate any revenue for the co-op, only delivery of services to. So the sales and marketing arm are yet another drain on the already meager amounts earned from contract awards.

If there was surplus money to be made large for-profit contracting companies would be in here already doing some or all of this work.