Interpersonal comparisons of value are impossible.  The different valuations are very stark between a prince and a pleb.  There may be goods the pleb values very highly, and the prince places relatively little value on that same good.  The differences are vast in this case, but the crux of the issue doesn’t change when the individuals change.  They can always have different valuations regardless of their social standing.

The subjective nature of valuations could be purely psychic.  It’s possible that an individual with a garden places an enormously high psychic value on it.  While another person, of the same social standing, may regard it as worthless.  Maybe even lower because it requires labor and the cost of upkeep.  We can’t compare the valuations between the two.  It’s absolutely ridiculous to place and objective valuation on this.

Value is placed on the good by the valuing subject.  It’s absurd to say this has a utility of ten.  This is meaningless.  One person might rank it as such and another good a five.  Another person can have a reverse preference order.  An objective unit of utility is impossible.  Even assigning a unit of utility to an individual is useless.  It’s ridiculous to say this is worth ten utilities and that’s five utilities.  All he would have to say is: I prefer this to that.

The individual is evaluating how much good they’ll derive from it.  The individual is appraising or estimating the good in question.  This can range from a garden to much more.  It’s very different to appraise something in money, and to estimate the psychic benefit one can gain from it.  An appraisement is what the good can—likely—fetch on the market.  An estimation is like saying: I’ll derive a psychic benefit from it.

There is no way interpersonal comparisons can be made.  The argument to steal from the rich and give to the poor is based on interpersonal comparisons of utility.  One could assume the rich man would derive more utility from the money.  This would justify transfers from the poor to the rich.  It’s easy to see this is absurd.  These ideas are based on gross error.  Different people derive different utility from a good.  Utility will never be universal.

Reference

Murray Rothbard; Man, Economy, and State