My responses, then the commentary, ok?  My kids are almost 3 and just turned 6.

1) In certain circumstances, I already leave my kids alone in the car. Times when I have done this include: when it is very cold outside and I have to run up to the door at M’s school to pick her up (safer for L buckled in the warm car than me carrying her on slippery ice and snow or in  sub-zero weather), if I am running into Starbucks and parked near the door (though I can’t actually see the car the whole time), running in to a convenience store to grab milk or something, and once even at the library to pick up a reserve book. Actually, I am more comfortable doing this with L than with M, because she can not get out of her carseat herself to cause trouble. If it isn’t hot outside and the doors are locked/car isn’t running, I don’t see how it could be called “dangerous” to leave the kid for a couple minutes.  I wouldn’t feel comfortable in a big parking lot with a bunch of people though (mall, grocery store, etc.)

2) Haven’t left M home alone yet, but I think it sounds extreme to wait until she is 10 before I can run out and pick up a pizza without dragging her along. I am more comfortable with the idea of her alone in the house (where she is very familiar with the rules) than I am with her outside alone.

3) Mr. A and I have had a long-running argument about this  one.  He would have let M play alone in the yard when she was barely 4, but I said no.  We are just starting to let M play outside without direct supervision.  Only in our front yard, if the door is open because our backyard has a path to a pretty busy street.  Only in the grass but not the road (even though we live on a dead end).

4) I don’t know about this one.  Certainly not alone at the park any time soon.

5) She will spend the night in a stranger’s home when hell freezes over.  (Ok, I know this will eventually probably happen, but right now I can not even imaging OKing it.)

Reading through the comments, it seems that there is a big range in what people consider to be reasonable risks and dangers.  I personally don’t worry much about my kids getting kidnapped by strangers.  According to this article, stranger kidnappings happen less than 100 times a year.  I just don’t buy the hype.

I would be much more worried about them being molested by an acquaintance who I didn’t know well (thus my answer to #5).  I am very concerned about them getting run over by cars which makes me feel very cautious about #3 and #4.  And like  Spacemom mentioned, I am also pretty worried about drowning and guns, though it would be very hard for me to ask another parent about their weapons.  I would also worry that they were misbehaving and acting like the other hooligans at the park if I wasn’t there to monitor them (#4).

I am a big believer in letting kids earn the right to have more freedom. M has not demonstrated a consistent ability to watch for cars and follow rules outside (where distractions abound) when I am not prompting her, so she can’t ride her bike or play in the street without an adult. We are just now testing her ability to be in the yard alone, so she is on a pretty short leash.  On the other hand, she very clearly knows the rules in the house and can be trusted to follow them, so I think I would feel comfortable leaving her alone in the house (briefly) if she was ok with it.

Like Dawn and a few other people mentioned, I would also not be OK with leaving M in a position where she was responsible for L — if L wasn’t old enough to be responsible on her own.  My parents left me in charge of my 8 year old sister while they worked(8 hrs a day, I think)  for an entire summer when I was 11.  It was too much responsibility and my sister wouldn’t listen to me at all.  I think there is a place for an older sibling to take the responsibility for looking after a younger sibling, but too much responsibility too soon worries me.   You may recall how freaked out I was by this incident at the park.  One of my biggest concerns was something happening to the younger kid and the older kid getting blamed when it was not developmentally appropriate for him to be in charge of such a young child.

FYI, I checked and there are no laws in my state regarding either leaving your kid alone in the car or in the house. (So don’t bother calling the cops on me!  heh.)

Also, thank you to all my lovely commenters for restricting your comments to your own kids and not getting judgmental about what other people do!