Is it normal that my parents are still friends that have done "immoral" things?

The title probably sounds weird, but there's so much I can put in a title, so I'm going to try to explain this the best that I can...

So, I consider my parents to be judgmental about certain things. They would disagree with me, but I think they are. It mostly stems down to what they consider moral and what they don't. For example, my dad doesn't believe in pre-marital sex, or living together with a boyfriend or a girlfriend when you're not married, and while my mom is more accepting of older people who do these things, she completely disapproves of teenagers having sex, and using abortion as a form of birth control. And as most parents do, they disapprove of drugs, underage drinking, hardcore partying, and other stereotypical stupid shit that teenagers do. My mom also doesn't like being around people who constantly need a boyfriend or a girlfriend, and my dad is all about "doing the right thing".

Here's the thing, though: it's not that my parents have done any of these things themselves, it's that they have friends who have done these exact things in their past.

And it's not that these people have been friends with my parents for a view months, or even a few years, these are people that my parents have known for decades. They've been with them when they've done these things that my parents disapprove of.

For example, my mom is still friends with a group of girls she was friends with in high school, but they did a lot of stupid shit when they were teenagers. They were all boy crazy, partied hard, none of them went to college, and one of them got an abortion before she graduated. As for my dad, one of his old college friends was a total party animal when he was in college, and one of my dad's BFFs currently lives with his girlfriend.

And here's where I'm frustrated; I can't believe that even though these people have done all of these immoral things when they were younger, my parents are still friends with them. My parents are friends with people who have done the exact things that they tell me NOT to do. My parents continued to be friends with people that have done things that they disapprove of.

My parents say that their friends are good people, despite what they've done in their past. That they've grown out of their stupid phase a long time ago, and that they're better people.

But look at it from my point of view: my views about what's right and what's wrong, what's moral, and what's immoral have mostly been developed through my parents opinion, from what THEY think is right and wrong. I've been taught my THEM what is right and wrong, and have become even more judgmental than they could have ever been.

I'm judging people based on their actions, because I feel like that's what I've been TAUGHT, because that's what I always thought that's what was expected of me; to judge someone else who has done something immoral, and feel good about myself for never doing what they did, whether it's doing drugs, or partying hard. They can deny it all they want, but I've been taught by both my parents and the society that I live in to judge people for doing what I don't think is moral.

So what do they honestly expect when I find out that they're still friends with people who've done immoral things? Be okay with it? Be okay that my parents are a-okay with still having friendships with people that did stupid, awful things in the past that they would probably disown ME for? Now that I'm older, they expect me to be tolerant of things that other people have done when I was RAISED to be intolerant?

If I had friends that did drugs, or lived with their boyfriend, or had abortions in the past, you can bet that my parents would judge them. You can bet that my parents would have an issue with them, no matter how nice they are, or no matter how much they've changed. No matter how nice my parents would be to these friends of mine, deep down, they would look down on them because they did something that they disapprove of. So why should I be tolerant of THEIR friends, when I know they wouldn't be tolerant of MINE?

TL;DR: My parents have old friends that have done things in their past that they consider immoral, and they don't judge them for it. Being raised on being judgmental of immoral people, this frustrates me since I think that my parents are being hypocrites for doing so. is it normal that my parents are still friends with them? is it normal that I think it's weird???

(Holy shit, this is a really long post... I'm sorry it's so long, but this has been on my mind for the longest time now, and I really want someone else's opinion on this).