This is another problem with using the market rate to drive salary expectations. Roles aren't the same between companies even if titles or grades are. Basing a salary on what other companies pay "Developer L5" assumes that "Developer L5" is the same job everywhere, and it really isn't.

We all know people at companies that give devs 'lesser' titles (and lower wages) and then expect the person to do the work of the higher title role.