From a service point of view I have always found that it is the quality of the paint that is more important than the colour. Trucks that have good paint jobs will have less dammage caused by the operator because they care more about a nice looking machine rather than some old scratched up piece of junk that they have to drive.
We are required by law to have flashing lights and back up alarms so the colour of the lift does not have as great a difference to the safety of pedestrians.