Fog nets are a good and legit technology. But they only work in very specific circumstances: fog. Very few places have that kind of weather.

Basically the shortcut they're using is that the water is already in liquid form; fog is made of tiny droplets of liquid water. The net is just there to collect that liquid.

In the much more common circumstance when the water has evaporated into gaseous form, the only way you can turn it back into a liquid is by extracting enough heat from the gaseous water to condense it. That will always take a lot of energy.