DirectTV Now and PS Vue don't have any way to block certain shows. I use an Apple TV where you can require a passcode to get into the app but that stinks if the kids just want to watch a cartoon...they have to come get me to punch in the code to open the app.
I'm sure that these various streaming options will add this type of stuff but right now they don't have it.
Oh yeah, and I have not been impressed with the 3 streaming services' UI...it just is not that user friendly. I am seriously contemplating going back to Dish in a week when football season starts.