This is the whole demonstrated preference thing. I don't buy it myself, but that's a debate for another time. What I mean by subjectively is that I will value one person's life more than another person's life, or I could think that I want that $1,000,000 more than a rich person wants it, but that's just all in my head. To compare utility functions and work from demonstrated preference usually - not always - is a precursor to some kind of authoritarian scheme. I can't say there is anything like that coming, but it does set off some alarm bells. Anyway, this is not something I can substantiate right now.