I have both computers and air conditioning and neither consume water.
I’m assuming of course that evaporation cooling is cheaper and consumes less energy than closed cycle cooling with a forced air heat sink.
Much of the day/season, evaporative cooling is not needed and data centers can pull in outside air. Ultimately you state the main reason in your comment: using outside air + evaporative cooling is cheaper and consumes less power than any other approach.
In a lot of cases, even if the server chips themselves are liquid cooled (for example, in an NVIDIA GB200 rack), then liquid is then air cooled through a cooling distribution unit (basically a giant radiator.
Today's supercomputers (AI or not) can't cool themselves off with air. Too much heat in a too confined space. Direct Liquid Cooling is a must.
However, you can use closed-loop liquid cooling (like Europe), but open-loop is cheaper since it skips the "pump the heat out from water to atmosphere" part and "who cares about the water anyway, there's monies to be made".
Putting money above the environment always makes me angry though. It's like burning the walls of your house to stay warm.
Yet look at the prices on e.g. Hetzner and how profitable US cloud is. They can easily afford to do closed loop.
Whenever there’s a real environmental problem the answer is usually “there’s a right way to do it that lacks these issues but it’s slightly more expensive.”