It really is that easy.

If someone is transmitting across the airwaves, be it a broadcasting company or a walkie talkie, all you need is a suitably tuned antenna to pick up the signal loud and clear.
So many things can act as antenna, including dental fillings, you only need a random/coincidental matching of radio signal (wavelength) and antenna length to pick something up.

The only differences between a radio station and a walkie talkie, are the wavelengths and the power of the transmitter.
The only difference between a loop of wire and a radio antenna are that the former can randomly act as an antenna and the later was designed as an antenna.