Last Sunday had very bad encounter with taxis.
Me and a friend were trying to hail taxis at Battery Road in Raffles Place at around 9:30pm. At that time the place was quite "dead", hardly anyone around. We saw 2 taxis with the green "TAXI" light on and driving pass us, refusing to stop, and immediately cutting to the opposite lane (Battery Road is 2 lane road). After they drove pass, one went hiding in a side road and one hid inside a building's driveway.
Expecting us to call for taxi, then "ZOOM!" instant arrival of instant taxis?
Then I tried something after the first empty, I hailed with my friend, to test if 2 people hailing ("many customers") will cause the taxi to stop. No, it didn't stop.
We gave up, he decided to catch a taxi from Chinatown and I took a bus home instead.
Have no problems hailing taxis around 6:30am. Some drivers are very friendly though, but it's the black sheeps that spoil everything.