[mcguire]

Timescale.

An older employee with experience can often see and avoid problems before they occur. A younger, inexperienced employee will not and will have to find the problem and attempt to fix it, usually three or four times before the problem is actually solved.

So, for six or twelve months, the employer can sail along gloriously, enjoying the benefits of cheaper employees. Until the bill comes due. And at that time no one can really help them except their current employees, who are the only ones who understand the history-dependent system they've built.

Fortunately, the time scales that most employers operate at rarely exceeds six to twelve months.