Yeah I agree with you but most turtles you see on TM ect are in 100L tanks have shell issues and the water is filthy. Not saying all turtles are kept like this but some of them sure are. A lot of people buy turtles for children and don't pay a lot of attention to them, after a while they get bored with them and don't care for them properly; not doing frequent water changes turning of light scrubbing some algae. But yes RES are easy to care for if you have some common sense and do some research on them before hand.
Yeah my mums mate has a turtle, good condition ect. He went to go and get a new substrate for his turtle and the sales person had sold him small stones, small enough for the turtle to eat. I have informed him to remove the rocks as it leads to impaction then thing don't get easier for the turtle. I might go out and buy some sand for him in the weekend and rinse it for him.