Some city drivers work more than 12 hours daily. Some have regular stops that require phone calls. Having the same handheld allows those work phone numbers to be stored on a work phone.
In most cases , the drivers that have equipment assigned to them ( or try to take responsibility for a certain piece of equipment ) tend to take better care of that equipment.
From what I've seen , management rarely gets involved to stop abuse of the equipment drivers use ( misplaced handhelds , pallet jacks left here and there , tractors trashed....)
Why wouldn't a person be proactive and try and keep a tractor or handheld clean and/or operating correctly? ( away from the person or people trashing it )