Well, radio is a shared medium, so governments typically require passing some sort of certification to allow radio devices to operate in their jurisdiction. Mos

Well, radio is a shared medium, so governments typically require passing some sort of certification to allow radio devices to operate in their jurisdiction. Most governments are pretty lenient, pass a set of clearly defined emissions thresholds or compliance to communications protocols verivied by a third party, others may choose to add additional requirements. The general exception to this are ham (amateur) radios, they usually have exemptions carved into frequency plans so they can run anything from fully original designs over kit builds to ready-to-operate stuff.