Poteroo, I agree - the airlines are not for everyone and not the be all and end all, but when considering return on effort in terms of terms and conditions they are a much better place than GA.
That said absolutely there are people who do not want to go to the airlines, there are some who did but for whatever reason it didn't happen and others who want to but have not gotten there yet.
If an organisation is associated with a major airline and wants to train a kazillion ab initio pilots a year, then they need instructors of all grades and experience.
If they offer a career pathway then the instructor can decide for themselves whether they wish to avail themselves of that opportunity. If they don't offer it, the ones that do want to go to airlines will abandon them when the opportunity arises and they will see the throughput that this brings.
Give people a pathway and you will find people are generally happier, even if they themselves don't want to go that route, the ability to do so if they change their mind later is a powerful motivator.
And even things like staff travel, uniforms, crew benefits and other small items show the instructors that they are valued and not some necessary distraction off to the side.
But I am not a manager so what would I know