There are many kinds of fluorescent lamps. Those neon tubes that tend to flicker before starting up is the hot cathode type. It has a circuit like this:
In these types a starting circuit randomly opens causing a inductive voltage surge in the tube to strike it. Generally the grid voltage is not enough to maintain the glow discharge, so the circuit tries again. Between the attempts the electrodes of the tube is being heated. When they got hot enough they emit electrons via the thermionic emission. This hot spot turns the glow into much brighter arc discharge which can be maintained on a much lower voltage. When the lamp is running cathodes are kept hot by the ion/electron bombardment.
CFL bumbs use cold cathodes. But this doesn't mean that their cathodes remain cold: when they struck, the grid voltage can maintain the glow due to their small size, which will turn into an arc as the cathodes heat up by the ion bombardment and the bumb gradually brightens up.
So if you turn off the lamp for few seconds the cathodes don't have time to cool down and the starting circuit can start the tube on the first try.