Underhill,
If children are taught from a very early age they are completely safe around guns or any other tool that could cause injury or death. My kids were taught as soon as they saw my gun on the table that it was dad's tool and that they had to ask if they wanted to handle it. They asked often and I taught them from the beginning that they had to check and clear the weapon before they could handle it. I would clear the weapon for them (they were 3 and 5 years old) because they didn't have the strength to pull the trigger or open the cylinder. They handled all the guns and knew how to check and clear them before they could even pull the trigger on them. Both my daughter and my son went shooting with me before they could fire the guns. They were a big hit at the police range and they liked to show off how they could check the guns and yell, "clear" when they were sure the guns were unloaded. By the age of 7 or 8 they were shooting at 25 yard targets and having a great time shooting groups that were smaller than some of the officers doing their "monthly ammo burn". My guns were loaded and all over the house and they held no fascination for my kids at all - they were just another of dad's tools that were always there. When they had friends over the friends might ask and then they would come to me and I would monitor the steps just to make sure the new kid wasn't going to do something ignorent but my kids showed them how to check and clear the gun and then made them do the same thing. It must have seemed like a lot of work because they never asked a second time and my kids mostly ignored the guns once they could shoot with me at the range, unless I was going to the range - they would miss cake and ice cream to shoot with their dad.
I never locked any of my guns up because if they are locked away then kids are curious about them and you can't get to them in time if you need them.
My dad kept the guns locked away and the ammo locked in a separate place and I was curious enough to pick the locks as a 10 year old and fire one of the guns out the bedroom window. Locks don't make it impossible to get to the guns. It just takes a bit of determination and time. I can still pick a lock - it has saved me and friends a call to the locksmith quite a few times.
If someone is determined enough you can't prevent them from doing wrong. With my kids it was better to remove the mystery early on and show them the way guns should be handled. This kept them out of harms way.
On the other hand if you don't like spending time with your kids and would rather ignore their interests then maybe a gun safe is right for you. Don't expect to be able to save them if someone breaks into your house - you can't get to those locked up guns as fast as he can bash your head in with a baseball bat.
I'm sorry but that just isn't true.
There were kids just down the street growing up who's father a member of the Rod and Gun club, and took his kids there to shoot regularly.
One of them was killed when the other, who thought he knew what he was doing, thought the gun was empty and was showing it off. He didn't realize there was one in the chamber and shot his sister.
The problem is, you seem to be under the delusion that just teaching your kids what is right means they will always do it. I find it hard to believe that any parent could be so naive. It wasn't true with me or my friends, and it isn't true with my own kids.
The best medicine is both. I teach my kids and keep the guns locked up. They have no need to learn how to pick a lock (which would be tough with a safe) because all they have to do is ask and I will take them shooting...
I have no idea where you live but where I live I don't feel the need to keep guns unlocked and lying around at all times. I don't know anyone who does.