Earlier quoted context omitted.
Not true. Low power FM and AM stations are allowed. https://www.fcc.gov/media/radio/low-power-radio-general-info...
And there's ISM bands as well. However, all of these unlicensed bands have strict limits. For any of the fun stuff, you need an amateur radio license :-)
> However, all of these unlicensed bands have strict limits.
This is absolutely key here - even in unlicensed bands one cannot just start using the spectrum without careful consideration of regulations for that spectrum.
When I was working in the 902-928 Mhz (FCC and similar) and 860s (for ETSI) for RFID we had to do a lot of work to ensure our transmit power, power ramp up, frequency hopping and listen before talk were all implemented properly and demonstrable for certification. It was not trivial.