Everyone has grown up in a different place with different parents who choose to raise their children differently. Some people had parents that didn't really care what their children did. Other people grew up with parents were a lot stricter about where their children went, what time they came home, and who they were spending time with.
Just like everything in life, there are pros and cons to both of these parenting styles. In my 19 years, I have observed a few things about people who grew up with strict parents. Sometimes the children have that desire to do the things they want, so a sneaky child is created. They sneak out or lie about what they're doing because they don't want their parents to tell them no. Or a strict parent can create a child who doesn't really care to go out or do anything. Since they never really went and did things growing up, they tend to stick to this lifestyle even when they are older.
But lenient parents can also lead to a sneaky, wild child. Depending on how laid back the parents are, this can also create a disrespectful person who doesn't understand the concept of consequences and discipline.
Let's be real, most of us grew up with strict parents, but either way, it really shows how we were raised.
If we're being honest, the only way to get a real answer is to ask the parents themselves. If I had to guess, I would say that it's because the parents are just scared of what their children could get into if they don't monitor their lives.
On the other hand, I believe that some parents are more laid back because they just want to be their child's friend. They don't want to tell them no and cause a rift in the relationship so they just kind of let them do what they want to do.
At the end of the day, whichever way our parents chose to raise us is part of what makes us who we are today. There are probably tons of reasons why parents chose to raise their children the way they do, but everything is usually done out of love.