I had read some interesting articles of late regarding Visual Psychology (that's right, there are such things as Visual Psychologist!). White vehicles are researched as being the most overtly recognisable colour on Australian Roads, however the percentage of white vehicles, trucks, cars, etc incurs a certain level of commonalities. Other emergency services throughout the world have recognised this and you would note that in the UK the base line colour for most Ambulances is Yellow or Silver (for response cars).
With saying this, white is also probably the most cost effective colour to purchase as most, if not all vehicle manufacturers would have a white baseline model available. The MFS in the 1990s brought a number of Isuzu 500 Dual Cabs as a light pumper body, and had to have them repainted, at a significant cost to the tax payer. So I at the end of the day can see the justification of white vehicles.
However... Personal view, and being one who like to stand out of the crowd! I like the ACTFB fleet colour, fluro yellow/green. Definitely Stands Out