Tom Dolan has an excellent blog post which touches, in part, on comparative cost.
If you're working for, say, a TV company - then you know exactly how much an hour of TV programming costs on average. If you want to do something like build a website, it's quite natural for people to evaluate its budget in terms of how many hours of TV it costs.
That can be a useful metric. It allows people to benchmark the impact your non-core project is having against the investment. But, in my experience, it can also be toxic.
One of the challenges I faced when working with the NHS was that lots of people view the health service only in terms of Nurses. And any change that you propose will instantly be compared with a Nurse's salary.
It's disturbingly easy to say "We need a new payroll system? But that will cost the same as ONE THOUSAND NURSES!"
But, of course, without a proper payroll system you will have zero nurses. And - whisper it - one thousand nurses isn't a huge number in context of the total number of nurses in the UK.
Now, don't get me wrong; I love nurses. But the NHS is also doctors, porters, receptionists, cleaners, and many more people. It is also buildings, TV screens, MRI machines, door handles, and scalpels. The NHS is computer systems, hardware, software, cloud processing, and giant stores of data.
Should we have more nurses? Yes! Should they be paid better? Yes! Can we improve the NHS without capital investment in technology? No!
Technology should be a generator of efficiencies. I'm aware that's not always the case and that a mismanaged project can be worse than no project at all. But comparing every piece of technology to a nurse's salary is an emotional sleight of hand which prevents any progress.