"Taxis have lit lights on top of the car and special plates"
I read previously that they have special plates, but nothing about "lit lights on top". Even Natalee's friends said "Natalee got into a taxi with J".
There was a picture posted way back in one of the earlier threads that showed a taxi with the lit taxi sign up on top of the car. I would think that it woud be easier to spot than trying to catch the first two letters of a plate that may be moving.
Taxis have a vested interest in making sure the tourist can spot them easily. It's how they make their money.