Either because the writer, director or producer didn't do their research on the old flims, comics or cartoon series or she is truly is a diva with a bad attitude and refused to dye her hair.....however they could have got a good Real Hair wig.
Or maybe that she is a pin up for guys and they like her dark brown-black hair.....so they might have decide to go for the pin up with boobs and lips factor for the flim. You would think if they are going to remake Teenage Mutant Ninji Turtles you would think they would want to do it with a bit of sensitivity to the people who remember the cartoon, flims or comics.
