Why don't kids ever listen?

Ok, The only way i would say to my niece is raising my voice is when she listen. But when i say it nice or in a normal voice never listen and end up with bumps, scratch, bites, bruises. Why is it that when you raise you're voice and mean business that's when they listen. And never listen when you say it no honey don't do that you're going to get you're head stuck in that whole. Then gets her head stuck in the whole. Or get stung by bees when i say it nicely when she doesn't listen. Stands there with swarms of bees stares and let her self get stung. Still standing there. Why don't she run too when she knows when she's getting stung? She's almost 8yrs old she knows what bees are. Is it the tone of voice that make them listen or is it the way that's been told? I worked with kids before camp counselor, babysit then it's my niece. Why don't some kids ever listen when it comes to dangerous situations like this?