FFS Friday - One Thing I Don't Ask My Kids to Do

I don't make my children share. 
I know we're all about teaching children to share, it's so important etc. But is it really? Adults don't share so why should children? They won't be expected to share when they grow up and yet we expect these small people who have very little control over their lives to share the one thing that they can have control over, their toys.
Not only do we expect them to share with their siblings and friends, we also expect them to share with strangers who they meet at the park, friends kids who they're meeting for the first time, kids at school etc. It doesn't make sense to me. 
Can you imagine if someone came to our house, walked into our bedroom and started using our things? We'd be so angry and yet we expect our children to be okay with that happening to them. Even my BFF who I've known for twenty years wouldn't go in to my room and go through my things. Likewise I don't use her things without asking.
I tell my boys that we share with the people we love. I also tell them that it's okay for them to have special toys that they don't want to share but it'd be nice if they have some toys that they do share. This works really well for us. They share the toys that aren't really precious to them and don't share their special toys.  
If they don't want to share something that's okay. 
I don't understand why we make sharing such a big deal. MIL got annoyed with me a few weeks ago when I told her I don't make the boys share. Even after I explained why I don't make them share she was still annoyed. Not my problem. 
Funny how people think they have the right to question other peoples parenting decisions. They wouldn't question or criticize their diet choices and yet they question their parenting. IMHO people should mind their own business.