It usually only makes sense to invest in a good you own. An employer might train a worker, only to have the worker jump ship to a competitor immediately after receiving training.

Historical labor force norms made it more difficult to change jobs which mitigated this problem. In a sense the employer owned the worker and training made sense. Workers now own themselves, so it's up to the worker to invest in their own training.

Do we really want to go back to the older era?