This problem has been discussed for years. ATC's definition of WET is not the same as the performance engineers. We calculate performance increments due to depth of water, % of runway covered etc. This effects MOW for take off & landing not only for the weight allowed by length, but also crosswind limits. It could cause unnecessary diversions. We are interested in depth of H2O, the ATC, stuck in their glass towers, use change in colour. (is that still the case). You can get a change of colour if a squadron of swallows pee on the surface. Even damp is dubious.
For those who've operated in SE Asia I've heard astonishment when UK/EU ATC declare wet. They know what wet is. I suspect that, if the assessment and declaration from a distance is only visual, then there is some back-side covering. It is that era; cover yourself and ignore the consequences to others.
I've had this dilemma when, on a severe clear day, ATC was declaring wet x3 and the cross wind was right on wet limits, with gusts a little over. I could see the runway and it was not affected by water, it was slightly shiny and may have had some puddles after a shower. Now, the sun was beating down on it and the surface had drained to shiny. You can see how much water is there when reversers are activated. I watch a landing after ours and the spray was negligible.
ATC is a service provider to us in the chain of safe operations. We need accurate data/info to make safe & commercial decisions. The contaminated runway assessment is undergoing scientific change to try and help this outcome. Why is dry/damp/wet assessment not included in this process? After all it is about an accurate runway state determination.
In my later years I did consider that TAFs had become more pessimistic. I wonder if this airing on the worse side is a back-side covering issue?