Why does amateur radio not support CB band

"It should include all standard HAM radio frequencies in both Analog and Digital but also be capable to Rx-Tx on 26.965 to 27.405 MHz AM and FM CB Radio" This is our friend Patrick's suggestion to HM1, but it has been verified that almost none The radio supports sending and receiving of two frequency bands at the same time, why? I consulted with colleagues in the Regulatory Department specifically on this issue.

Different users

CB is short for Citizens Band, which is a civil band that every citizen can use; amateur radio is a radio station that only a few people with certain theoretical and operational knowledge and who have obtained an amateur radio operating license can operate, so the users are very different. 

Prohibited by law

Part 95 of the United States stipulates that CB radio operators are prohibited from communicating with non-CB radio stations, especially the amateur frequency band 26-30 MHz; the preface of the Canadian RSS 236 standard also clearly stipulates that the radio station should be used with equipment that requires certificates, and amateurs are authorized and certified. No certificate is required.