Money is the best tool we have to measure that. Sure it has pathological cases, but overall it's the least bad version to assign value. In the government case it's much worse at this since it's not voluntary and measuring aggregate government services vs. tax. The consumption/price is completely unrelated, etc.
>I know of several people that are 'employed' but net negatives and society is way better off with that arrangement than having them on the streets.
If we are heading towards an economy with labour shortage (demographics collapse), taking up people from the economy and keeping them employed with a useless skillset is going to be a double negative.