I think we need to move away from the "weather diversion" distraction and look at what the recommendation actually said.
Precautionary landings should be free of charge.
Why?
Because it might just save a life or several.
We can argue about whether the cost should come into it, or whether the pilot should have thought more carefully about the weather, or maybe should have selected seven alternates instead of two - but at the end of the day human nature being what it is, waiving a landing fee to "tempt" a troubled pilot down seems a very small price to pay in the name of enhanced safety and I am amazed people try to justify the 18 airfields not doing this.