If you're good you'll get paid if you're not you won't. You agree the metrics, the success levels/triggers and the reward structure with the client in advance and proceed from there.

Most of the time the government is trying to change behaviour or perception. The commercial world tends to measure success in cold hard sales, there are many methods and devices for tracking the effect of campaigns and marketing activity - which could also be applied to a government campaign.

Often research will be done to determine the baseline at time of commencement.

A good marketeer or strategist takes into account all the external factors and variables when planning the campaign, from the creative to delivery to redemption - and that includes the client if necessary. Most agencies calculate and already know the success of every activity they undertake both for their own records and because their commercial clients already demand it.

If it makes department think harder and more strategically then great. It should shake up some agencies that see government as a cash cow with less responsibilities than the open market.

A marketing campaign is one thing but designing and delivering a tool for the client to use, modify and populate themselves (which you'd have no control over) is another. Should this come to pass, Puffbox should be ok!