>If it was completely luck, then they (hopefully) wouldn't do it.

I remember an article in Analog, a very long time ago, that touted how dowsing was used to locate mines in Vietnam. John W. Campbell was into a bunch of silly things.

https://www.latimes.com/books/la-ca-jc-astounding-20181115-s...

There was a guy who made millions more recently selling fake bomb detectors that were used in places like Iraq:

https://www.bbc.com/news/uk-22380368

If it was not real, would they use it in life and death situations? Yes, yes they would.