The FRTOL is an International requirement set by the International Telecommunications Union (ITU) who administer all radio regulations. All countries that abide by the ITU requirements will issue radio licences in accordance with the ITU General Radio Regulations of which Article 37 specfically covers Flight Radiotelephone Certificates.
The UK Issue FRTOLs based upon the ITU requirements, some other States either chose not to comply, or interpret the rules differently.
i really think that RT should be part of the PPL syllabus, the CAA always speak about how safety should be first within aviation.
If you read the syllabus, you would find that it has been for over 17 years! A second licence is required because it is a seperate privilege that may be held by a variety of flight crew members as well as persons with no other flight crew licence.
FRTOL "Restricted"
means that the radio must be tuned by switches that select predetermined friequences. This was distinct from the Flight Telephony Operator's (General ) Licence that was issued to professional radio operators, who could use radios that were manually tuned. As such radios have not existed for many years and the General licence predates the CAA, both the General licence and the word "Restricted" were eliminated from the ANO in 1998.
Any FRTOL permits operation on VHF and UHF frequencies, where available; the limitation if any, is on frequencies below 60MHz.