Yeah I think you have to go with the subjective meaning. I don't think you can talk about objective benefits, otherwise things go to hell very quickly. Where do drugs (legal or illegal), alcohol, tobacco, sugary foods, fatty foods, fast cars, hybrids, condoms, birth control pills, church donations, etc all fall?

It really depends on who you are. There's no way to have an objective arbiter who determines what is actually beneficial and what merely seems to be beneficial. At least that I know of. The problem seems intractable to me.

I didn't mean "the value we think they should be deriving." I meant that people can be mistaken (or mislead) about how much they value something even in the short term. If someone thinks they are buying a reliable car and gets a lemon, I think it's more correct to say "they didn't get the value they expected" then "their revealed preferences show they really wanted the lemon".

Ah yes, that makes much more sense.

I'm not sure this is a criticism of the proposal, but nothing I've said implicates an objective arbiter of value.