EpisparhDo you speak about NPCs or fully engineered player ships?
You were comparing the Vette's agility to a Python, and that makes sense only if the Vette is engineered and the Python is not. Unengineered Pythons are hard to find except as NPCs, and those are easy to tail even with FA On and no pips to ENG. A quick look at EDSY explains why. Clippers can change direction much faster, which is why I was considering a Clipper as my follow-up ship for gank evasion.
As far as engineered player ships are concerned, I've had quite a few gankers on my tail, and although they were more nimble than Vettes, they didn't get much time on target with fixed weapons either. If small ships were easy to hit, there would be no point in using them. Turrets may miss a shieldless stealth Sidey most of the time, but that's OK because a few lucky hits suffice to take it out, and the likelihood of those occurring increases with the duration of the fight.
The flaw of the Vette IMHO wasn't the turrets but the shields. They were wearing down surprisingly fast from that class 1 beam + rail.