The point is that hitting him with her car would NOT have been any kind of manslaughter if she had gotten help for him. The accident didn't kill him. Her failure to call for help, take him to a place where he could get medical attention, or render aid herself is why he died.
She would have gotten a DWI (or whatever the equivalent is in TX) if she hadn't reacted the way she did .... and perhaps another charge or two ..... but nothing like the mess she ended up in. What she did was murder the man through her negligance, IMO.
I agree. It just seemed like that was after the accident. I am not saying he didn't die at her hands. I just think it should have been tried differently.