Drow freed from Lolth, in isolation of another way being convincingly presented to - likely forced on - them, have had how many thousands of years of abusive culture hammered & manipulated into them. More likely than not they'll still develop an evil culture, though the structure of their society would likely shift due to power gaps. Given how they work either a single powerful demagogue or some sort of council system of the great houses.

Drow even under Lolth aren't necessarily evil but she set them up for biological rewards for evil whenever she can (there's little detail on this but I think that's concept's the source of the terrible "mother's ecstasy at womb murders" thing - good idea, bad example/implementation), on top of enforcing an ongoing culture of brutality and wickedness. Its how most of the evil deities still allow for Free-will to empower their Faith. They combine physiological reward hijacking, adding aspects that encourage easier exclusion from others (isolation is good for limiting options), and rigorous and brutal cultural and societal reinforcement. It doesn't prevent good, but it gives far higher hurdles for an evil race to overcome.