First let me say that I completely respect your desire to keep your child safe. There are many parents out there that (I think) throw their children to the societal wolves.
At the same time that you are keeping your child safe, you also need to teach her how to be independent and how to keep herself safe. At 12, I think that burden falls on the side of telling your DD not to do things that you do not consider safe. But she is also at a delicate age where soon she will want to fly on her own and want to make her own decisions and want to decide her own fate. THAT is the very delicate tight rope that we must walk as parents. If we are too permissive then our kids may make bad choices just because the choices are there. If we are too restrictive then they might rebel and choose ANY decision that goes against our advice.
While I know that evil is everywhere, I also feel know that evil concentrates in "victim rich" environments. I know that term is abhorrent and I hate to use it, but it is a fact. I do not live in that type of environment and therefore I give my DD a little more freedom than if I did. At the same time, I teach her about evil and I have advise her from a young age that any person can be evil. We watch the crime shows, we discuss the awful abduction cases, etc. Sadly, she knows to trust no one (more to do with X than any crime shows...)
The thing is, you cannot control what other parents may allow your child to do while at their house. Even if you tell the other parent that you do not want your child to do xyz, that parent may allow it. Therefore, it is up to you to teach your child to keep themselves safe in all situations. Teach your child to NOT trust anyone who offers a ride, even a neighbor. Teach your child to steer clear of any wild animals, including "cute" but feral dogs and cats. Teach your child that adults do not ask favors or help of children, unless the adult is a parent.
For now, you can control who your child is with. But you will need to let her try her wings soon, in a couple of years. You need a strategy for that. While your protective nature of your DD should be commended when she is 12, if you do not adapt then it will be rebelled against, by her, when she is 14 or 15 or 16. And by 18 she will be an adult and will have to navigate the very scarey world on her own. You need to prepare her for that, not protect her from the reality of that.
I hope you do not think I am being harsh. I think you are doing EXACTLY what you should be doing with a 12 yr old daughter. But she will only be 12 for 1 year and I am advising you to prepare her for this world that can be both wonderful and awful so she needs to know how to protect herself.
Being the mother of a daughter is scary stuff.
(((hugs)))