Sure it isn't free, but remember, this person had made it all the way to the end of the process. The determination was made that they represented such a large gain, for the low salary they were paying, that it was worth the risk of that small cost to get an employee at a 30% reduction in salary.
If you are going to save 30% of $140k, that means you will save $42k. It would take a lot of interviews to make up that gap.
Mind letting me know where you work so I can avoid it? Interviewing is part of the job and needs to be accounted for. You don't just make your employees do overtime because you don't want to plan out your companies work well
If their other work falls behind because they spend too much time interviewing, well that is the company's problem. I have never worked with anyone that would stay late because they interviewed someone that day. That is ridiculous.
And as for staying late "to get the work done", what job do you work in where the work is ever "done"?