Harvesting free energy

The air is saturated with radio,wifi,5G etc waves that could be converted to free electricity.
How legal it is? Surely there is a huge economic incentive(you can have battery free devices, lights,etc) where the radiation is strong enough.
What if you live near a radio station?

Cellular phone @ 50 m from base station 10-4 – 10-2 W
https://www.intechopen.com/books/ict-energy-concepts-towards-zero-power-information-and-communication-technology/electromagnetic-radiation-energy-harvesting-the-rectenna-based-approach

Periodic shapes allow better absorption
https://phys.org/news/2015-04-harvesting-energy-electromagnetic.html

In Siegel’s case, “depending on the strength of the electromagnetic field,” his electromagnetic harvester can recharge one AA battery per day. He doesn’t specify, but presumably one-AA-per-day is when he’s sitting next to a huge power substation.
https://www.extremetech.com/extreme/148247-german-student-creates-electromagnetic-harvester-that-gathers-free-electricity-from-thin-air