SSB modulation for VHF mobile and handportable transceivers

For many years now single-sideband (SSB) modulation has been used for almost all speech communication channels in the short-wave (2¿30 MHz) bands. This is because SSB is the most spectrally efficient mode and does not waste transmitted power in redundant carrier components. Why has it not yet been adopted for use in the VHF and UHF land-mobile-radio bands?