Is this an issue? Should a nine-year old be expected to go to shul without bribery, or is this reasonable?
I don’t understand the question?
Are you asking if this is the best way to be mechanech the kid? Because it doesn’t sound like it- it sounds like you are asking if it is normal, and if it isn’t, then you think they should just humiliate the kid into going by berating him until he agrees to go. (Or hitting him, or taking away privileges.)
And why are you asking about someone elses kid? It’s not of your business. Just stick your nose back inside your own siddur.