Allows you to read and capture radio signals. This has a nice summary of the different radio bands and what travels over them.

https://terasense.com/terahertz-technology/radio-frequency-bands/

And they get to keep the money from the purchase.

Restrictive corporate environments who do not allow for custom software installation. I pay for it but with the VPN trick. I am on vanced and sponsor block as soon as I leave the work place. Sucks but that is one of the use cases.