[boulos]

I think it’s more nuanced than that (see my other comment).

If you have a false negative, then maybe they spread the disease more than they might have otherwise (unwittingly, but now with the “certainty” they don’t have it).

If you have a false positive, the main downside is from people who think “great, I’ve had it / got it, I’ll be immune shortly”. So that’s the main risk to them.

[loeg]

In addition to the points raised above, a false positive could also have negative impacts on income (unpaid sick leave to self-quarantine).

The false negative hypothesis is facile; even if you don't have it, you can still get it. Ignoring social distancing on that basis wouldn't be any more sensible than doing so without the test. To the extent that some people are just idiots, a false negative diagnosis does not change that.