In principle it sounds like a good idea to have any vehicles that are crossing the runway on the same frequency as aircraft that are using the runway. I don't know exactly what ICAO currently says on the subject but I can give a bit of info about what happens in the UK....
Many years ago I think that the UK introduced a requirement for vehicles crossing the runway to use the TWR frequency. I recall there was a lot of resistance to this on grounds of cost (for fitting equipment to vehicles, particularly those which only occasionally needed to go on a runway) and, in practice, it was actually done at very few airports. There were also some 'technical' objections that aeronautical band frequencies are for communication between aeronautical ground stations and aircraft stations and, thus, their use for communicating with vehicles contravened ITU regulations.
Where vehicles do/did use TWR frequencies I have heard stories of poor RTF discipline and operating practise which caused disruption to TWR operations. I suspect many of these stories are apocryphal but I had personal experience of this on one occasion where - with good intentions - a vehicle driver made a number of inappropriate transmissions on a TWR frequency.
Whatever the reasons and history, in the UK there are currently several recommendations on the RT arrangements for runway crossing - in my view, these recommendations are a good compromise. The recommendations are in a document called
CAP 670 ATS Safety Requirements and the relevant text is below:
6.2.2 Two-way radiotelephony communication facilities shall be provided for aerodrome (surface movement) control service for the purpose of controlling vehicles on the manoeuvring area, except where communication by a system of visual signals is deemed to be adequate.
NOTE: This communication facility is normally provided by UHF radio equipment and systems but the use of VHF Aeronautical Mobile Service frequencies may be permitted for ground to ground communications in specific circumstances.
Recommendation: Where conditions warrant, separate communication channels should be provided for the control of vehicles on the manoeuvring area.
Recommendation: VHF air-ground communications should be cross-coupled to UHF two-way radiotelephony communications for vehicles operating on the active runway.
NOTE: Cross-coupling between the VHF air-ground communications used for the control of aircraft and the UHF two-way radiotelephony communications used for the control of vehicles provides situational awareness for the aircrew, controller and operator of the vehicle. The vehicle operator is aware of any aircraft transmissions by monitoring the cross-coupled VHF Air-Ground Communications and has direct two-way radiotelephony communications with the controller. In some cases the transmissions from vehicles are re-transmitted to aircraft. As separate transmit and receive frequencies are used at UHF between the base station and vehicles, talkthrough facilities may be used to enable vehicles to hear one another.