You're free to define value to always be price, it's a matter of opinion and by my own logic it's a valid thing to do, but separating the two concepts makes things much clearer when market effects distort the price of something who's value doesn't seem to have changed.
> market effects distort the price of something who's value doesn't seem to have changed.
This is still making the mistake that value is independent of what people are freely willing to pay for it.
If these examples are too abstract for your taste, there are many other examples. No one pays for volunteer work (by definition), but there's lots of volunteer work that, if people stopped doing it, our society would grind to a halt. One example is open source software; most of the work which goes into it is unpaid, yet our industry cannot function without it. Another is parenting; most people aren't compensated for having & raising children - indeed, it costs them huge amounts of money - but there is no economy without people performing this function.
I submit there are more things in the economy than are dreamt of in this philosophy.
I contribute every day to Open Source software. The "pay" I get is not in terms of salary, there are many other benefits.
The negotiated final price is the value.
> When the oil futures went negative, it wasn't the case that the value of oil was negative
The value of the futures is different than the value of the oil itself. Besides, the end result of a future is taking delivery. Most futures contract buyers have no intention of taking delivery, and have no way to take delivery. That explains the negative value of those futures.
> I'd expand that you actually have to define what value means to you, relative to the context in which the discussion is taking place. You'll likely find yourself considering value from different perspectives in different situations
That doesn't change at all the fact that the value is determined by what someone is willing to pay for it. That value is different for different people, as you say.