I have 2 RES. One turtle lets me pet its shell gently and is interactive. I do this by sticking my hand in the water. The other turtle is very skittish and won't let me get near it. I am wondering why this is, that one turtle is friendly and interactive, and the other turtle is fearful and gets angry if you try to touch it. Everything else with these turtles is good though.
Each turtle has its own personality just like we humans do. Obviously one is much shyer than the other. Sometimes they will grow out of this to an extent, but not always.
Mine is the same way, he runs when he sees someone and hides, but if you stay still for a period of time he will get up and bask and let you watch him.