ESRB rating are a bit pointless.
In saying that, my brother is 10 years older than me so when I was a "yoof" I basically had all the games he had. After he left, when I was 14, my mum wasn't particularly bothered by me playing ultra-violent games, after a conversation she and I had after discovering me playing MKII when I was... awfully young.
Even then, buying games online doesn't require age verification, except for the occasional "are you 18?" tick boxes.
Artificially making the game longer with stupid side activities
Specifically in Mass Effect. In the first, the Mako segments on the planets. Basically have a big square with some interesting points, but there are hills everywhere, so it takes ages to explore with your little car, and doesn't add anything to the game. The side missions in the game are usually pretty interesting, and even affect the later games in the series, but getting to them is usually a pain in the arse.
In the second, they replaced the Mako with planet-scanning for resources, which basically involves moving your mouse/stick up and down while holding a button to scan a sphere. Sometimes you get a mission, often-times not. That's even worse than the Mako noise!