Is it just a matter of not being worth it? I see cooling towers releasing what appears to be a ton of steam, pretty high up. If that steam were captured at the top and allowed to condense, wouldn’t that result in a ton of water with a lot of gravitational potential energy? That water could then be released and used to power water turbines. Maybe I’m overestimating the amount of water being released as steam, or underestimating how much is needed to spin a water turbine to get a meaningful result, but it seems like wasted energy to me.
Short answer you are correct it’s not worth it. The massive cost of a bigger tower and gravity turbine aren’t worth the tiny energy you get.
This video covers the basics of how cooling towers work to reuse as much of the energy as is reasonable.
https://youtube.com/watch?v=tmbZVmXyOXM