If companies are investing wages, training opportunity cost, and other resources into having a productive workforce some time in the future, it would be rationa

If companies are investing wages, training opportunity cost, and other resources into having a productive workforce some time in the future, it would be rational (though not fair) to invest less in those workers who were less likely to be in the workforce in a couple of years. That is, one can view a wage not as a reward, but as a retainer. If companies aren't paying you to be nice to you for what you've done in the past, but are paying you on past performance as in indicator of what you'll do for them in the future, then it would be rational for them to take more factors into account when estimating your future output. Estimators of your probability of leaving the workforce would be one such factor. It's not fair, but it might be rational.