Only for 2 things.
I will tell a parent that their child's helmet is not on correctly and offer to help adjust it.
Also when someone is clearly in the wrong gear when climbing. Many recreational riders don't understand how to use gears and are either in the large chainring and/or a small cog when going up hill. A few times after talking to riders we went back to the bottom and there were amazed how much easier it was when in the right gear.
Otherwise they are on their own to learn the hard way.