Another newbie question...

I remember when I was taking the PAL course, I found it strange and frustrating that on many guns, if the safety was on, you couldn't open the action. At that time, it was mostly bolt-action rifles that I found that. Now that I have my first pistol, it's the same again: with the safety on, you can't pull back the slide.

Why is that? I'd prefer to leave the safety on all the time, except when I'm about to fire it. Why do I have to take it off safety before I can check if it's loaded?

- Ron