With 2.0, parents were given the ability to block certain functions on their child s handset including Safari, YouTube and whether or not anything could be downloaded from the App Store. Restrictions in 3.0 can bar children from listening to music branded as explicit and watching R and NC-17 movies. The feature also applies to apps helping parents keep their children away from violent games and other racy apps according to their explicatory ratings. It wasn t until the second iteration of iOS that Apple got serious.
Source: https://threatpost.com/parental-controls-2-0-3-0/91865/