Do you we ask friends and family before they get in the car if they have been to the loo?
No, because you can stop the car fairly easily. As I said, there's nothing makes someone want the loo more than knowing they can't go. I've had a few uncomfortable passengers saying "are we nearly there yet?", so now I gently remind people how long we'll be in the air before next being near a loo.
If they want the loo after 45 minutes they can wet themselves as far as I am concerned.
Not if I've got to clean the plane