Negotiating a union contract...

The XY problem is relevant to the difference between "interest" based bargaining (X) and "position" based bargaining (Y).

X = the employee's overall take-home pay has been stagnant for the last several years, while their cost of living continually increases; the employee needs more take-home pay.

Y = picking "you will not raise parking fees" as a hill to die on / the only "solution" to X that the employee is willing to accept.

Aiming for Y (taking a position) is aiming for a very specific and limited solution to the problem (X). It cuts the employee off from from the universe of solutions to the problem (X) by insisting that it only be solved in one very specific and limited way. If that way (Y) is, for whatever reason, objectionable to the employer, then there will be a stalemate -- a period of time where there is no solution to X, where a solution has to be acceptable to both sides.

If the employee can aim for X instead of Y, then the universe of solutions remains open / unrestricted, and the employer can be recruited to help find possible solutions to X. (Maybe it will turn out to be OK with the employee to raise parking rates, in exchange for a cost of living raise...)

This interest/position paradigm seems relevant to asking questions on SO, when OP asks for help making their position work. Sometimes you can cut to X by simply asking: "Why are you trying to do this?"; But I wonder if sometimes, aiming for Y isn't just as valuable. How many of us have ever tried to do something, just to see if we could? Anyone here running their own DNS server with some specific type of software for that very reason? :-) Might not be your best solution to X, but it's still interesting...