Different parenting philosophies. It's that simple. Going further, parents allow (or don't allow) behaviors and activities that they themselves model. Why do you think the mean girls at school always have that perfect, queen-bee mother? Why do you think that the super-competitive football quarterback's dad is the one getting kicked out of the game for yelling at the ref? ANd the quiet little bookworm's mom is always in the back of the room at open house and never volunteers for leading the class party?
Soooo, that being said, most parents pick and choose the things to be strict about that are the most important to them.
My kids are 13, 9, and 7 1/2.
In my house, we choose to be very strict about homework, being to practices on time, following through with a commitment, being kind, being honorable, and always exibiting integrity. We are HUGE on respect, and all three of my kids understand that teachers, coaches, and others are heros and deserve to have students/kids who try their best and make their job easy. It is non-negotiable. They say please, May I, and thank you withouot being prompted. They hold doors for people. They look people ini the eye when they talk to them and greet people when they see them, which is more than I can say for the majority of kids out there that just ignore my kids when they say hi.
I could care less where my kids sleep - if they want to camp out in the same room, that is fine with me as long as they go to sleep. They do not have a set bedtime, although I TRY to get the younger two in bed by 8-8:30pm on school nights. Weekends are sooo much more lax as long as they don't have an early game the next day. We never have had rules about TV time as long as their homework is done, but then again, my kids are always at sports or activities, so when they ARE home able to relax and watch TV, I kind of let them LOL. I do not like gang violence or shooting kind of movies, but my kids have watched all of the Lord of the Rings and Star Wars movies, and Hunger Games since there is a HUGE social message there. I have read all three books, so I am not sure I will let DS7 watch the next two until I see them first. However, I will NEVER rule out a movie or game based on the rating alone - that is SILLY. (see??!!! different views!)
As a comparison, I have a SIL who let's her kids watch TV on TV night only. They have a different "movie" night for pre-selected, G-Rated movies. They have family game night, which apparently is the only time they can play board games, according to my 13 year old who tried to play one once when he was there on non-game night. LOL She doesn't allow them to play outside alone, ride their bikes without her, or go to friends houses.
Yet, her kids are WILD. And have no respect for authority or other people's belongings. We were at an event together once, waiting, and the 10 year old was throwing rocks at the metal siding of the building. DH and I both told him to stop, his parents did nothing, and he continued to do it, looking at both DH and I with a defiant look. Oooohhh- kayyyyy. Whatever. Her kids are 12, 10, and 3.