First of all, the question is incorrect. Its correct form is: "Why not?" Since they call themselves the city of "a thousand and one nights," why not add a few red and blue lights ... to the most exotic cars in the world. This was just a manifestation of financial strength, like a skyscraper with a height of 828 m "Burj Khalifa" or the archipelago of artificial islands "Palm Islands".
In fact, the authorities themselves noted that these supercars would not be used for hot pursuits, but only for patrolling the tourist areas around the city. When the UAE runs out of oil, all the eggs will be in one tourist basket, that is, this fleet is just another attraction that produces a hypnotizing effect on tourists. Thus, the Arabs only maintain and renew their mirage in the desert.