The primary difference between my personality and my mother’s is that I consider a wide range of things to be fungible, while she apparently for every normal human activity has a checklist of necessary conditions for its occurrence. For instance, staying as long as possible at a friend’s house who is leaving for several months is a worthwhile and fulfilling activity only if my shit is not on the bedroom floor. For instance, when I am rushing back and forth trying to both leave for work five minutes ago and pack the car full of the work clothes I will need in the new place I am moving to after work that night in order to not have to live with concerns like this, it is wise and prudent and not a distraction to stop and drink a glass of milk.
Of course, the philosopher/mathematician in me cannot help but point out that if you define your terms correctly, then it is a trivial matter to make a system where every possible commodity is fungible the exact same as a system where many things are necessary: you just set the value of the supposedly “necessary” commodities high enough that it’s not practically possible for a fair exchange involving these goods to occur (it’s not quite that simple, you need to make sure that your necessary commodities are inexchangeable with “necessary” commodities which are actually less “necessary”, but this is simple: rank your necessary goods into tiers of exchangeability, and then (this is what I think is easiest), when assigning values to goods, assign them using a base-x system, where x is the greatest amount consumable of any good whatsoever multiplied by the greatest number of goods in any tier. Then assign your tiers successively greater digit places.
For instance, say that Sally is a being that is so short-lived that she can only consume 10 of any good. She also believes that consuming schnozzles to be worthless unless she has also consumed whutzits. In a universe where these are the only consumable goods, we can calculate Sally’s happiness as 10w + s, where w is the number of whutzits Sally has consumed and s is the number of schnozzles she has consumed. In other words, the Sally that has two schnozzles but no whutzits has a happiness of 2 – and any Sally that has a whutzit, trivially, will be happier.
(The only other further wrinkle that I can think of is that some goods can be thought of as necessary in some situations and not others. If you must deal with this, just define “good” to mean “state of the world” and that solves the problem neatly: For instance, if a whutzit without a schnozzle is also a worthless thing, then you just change the equation to be something like 100000…0x10 + 10000…0x1 + … 1000…0y10 + 100…0y1 +… + s, where x1 is the number of situations Sally exists and has at least one whutzit and only one schnozzle, x2 is the number of situations Sally exists and has at least one whutzit and two schnozzles, blah blah blah. Those are subscripts - you get what I mean.))