The shortage is narrower than people think
There is no general shortage of people who want industrial work. There is an acute shortage in specific skilled seats, and the two get talked about as if they were the same problem.
Treating a supervisor search like a maintenance search wastes effort in one direction and underestimates the difficulty in the other. The useful question is never whether the market is tight. It is whether it is tight for this particular seat.
Speed decides more outcomes than money
The operations that consistently land their first choice are not paying the most. They are deciding fastest. Feedback within a day, a second stage inside a week, an offer that does not need to travel through three people who are on holiday.
Strong candidates are usually in more than one process. The one that moves is very often the one that wins, and this is the cheapest advantage available to any employer.
Internal promotion is undersupported
Plenty of operations promote from within, which is right. Far fewer support the person afterwards. A supervisor moved into management without any change to how they are coached is being set up to struggle, and when they do it gets read as the wrong choice rather than the wrong support.
The thing nobody expects
The most common reason a strong candidate declines is not compensation, commute or the shift. It is that somewhere in the process they concluded the organisation was disorganised.
Interviews that start late. Two interviewers asking the same questions because they had not spoken. Nobody able to explain who the role reports to. Candidates read all of that as evidence about what working there would be like, and they are usually right.