Well, they do in a free market environment. Airline people are artificially locked to their employer (seniority system) so it's possible for us not to benefit from market forces under certain conditions.

Example, economy is hot, inflation and wages are up but you typically have to change jobs to enjoy the full benefit of market-driven wage inflation. Pilots don't do that, except at specific career points. Also if there's not a lot of retirements, then there may not be excess demand relative to the available applicant pool. Even if there IS a labor shortage, that doesn't naturally drive up wages for everybody ELSE on the list... we saw this 2017-2019, airlines wanted to increase the bottom of the FO scale but unions naturally wanted across the board increases.

Airlines want to pay junior FO's what they need to keep the applicants coming; everybody else on the list they want to pay as little as possible.

Market forces can have a slight effect on the upper scale during amenable periods... if their peer airlines have a higher scale, managers know that mediators are more likely to release a union for self-help so if somebody is behind the pack they have that incentive.