Why does any of this matter? Do you require a person proves their utility to you before you hold the door open for them? When a child falls and scrapes their knee, do you ask about their grades in school, or parents net worth, before lending them a hand?
My point: human society is deeply interwoven with sentimental behaviors that make zero sense in economic theory. You can try to apply all the models you want to model human compassion and it will get you nil.
But that doesn't mean we should optimize that out of societies. I think it's the most wonderful part of our societies, and if we were to remove it, we'd stop being humans.
If you're going to make the claim that people hold intrinsic value, people are going to challenge you for proof. Holding a door open for someone and asking questions doesn't necessarily indicate value. It could indicate personal interest. Empathy. Projection. Self-interest. The concept of altruism doesn't necessitate the belief that other life holds value at all. Altruism by its definition is giving without the expectation of return.
I think you make a good point re culture and tradition. Humans like many "valueless" activities. Some of these are hardcoded into our psyche through evolution. Some are for sentimental reasons. Some are religious. Some are enforced. Some are situational. Etc. I am not suggesting we eliminate those. I am simply agreeing with the top comment which is that we cannot force people to place any value on them. Some people do not see value in those traditions (or in other people). There is no objective way to prove them wrong.
But this is assuming we share the same set of axioms?
It sounds like you don't accept humans having intrinsic value as a core axiom. However, I do, and it makes zero sense to me to try and "prove" such a notion.
Apologies for the long-winded context, but I think it's important to address your point. You're alluding to some kind of intrinsic, self-evident value, and I would like to challenge you on that. Prove to me that this value exists. Prove to me it can be measured. To pre-empt your reply, I don't think you can. You might value a person in a certain way, but you can't ensure everyone else does. In fact you even accept this in your last sentence. A small group of people known to that individual would value them more than the other 8 billion people on the planet. Which is more or less what the person you replied to was explaining.