I sometimes try to understand the issue from an employer's point of view: why should they hire anyone on a permanent contract? I mean, in any field, not specifi

I sometimes try to understand the issue from an employer's point of view: why should they hire anyone on a permanent contract? I mean, in any field, not specifically in academia. Sure, you have an interest in keeping the most talented and important employees but I would expect that there is a large belly of mostly replaceable workers in any company of size. If that is actually true, wouldn't the cost of having to constantly retrain young recruits be offset by the savings you achieve by not keeping those around that have already moved up the salary ladder?