Medical insurance is the obvious example that comes to mind. If everyone is forced the pay for medical insurance (e.g. everyone is taxed for it), then the net r

Medical insurance is the obvious example that comes to mind. If everyone is forced the pay for medical insurance (e.g. everyone is taxed for it), then the net results is the same, the healthy people subsidise those the sick. Which is why in countries where medical care is not guaranteed through taxes (e.g. USA) insurance companies try to find out about any pre-existing conditions before they give you a rate; they try to figure out if you're in the healthy group which would otherwise be subsidizing the sick people, or you are one of those sick people. I say that without any value judgements one way or the other. The same is true with other forms of insurance. See broadly Adverse Selection, https://en.wikipedia.org/wiki/Adverse_selection https://en.wikipedia.org/wiki/Adverse_selection.