Perhaps my question sounded too general.
I pulled in the PP's quote as it referenced a particular instance in which the passengers were not over the limits. And, in that case, I stand by my comment about the TSA overstepping her/his authority. I didn't question whether TSA has the responsibility to enforce rules, I questioned their going beyond the rules in that particular case. Whether the children in that situation were potentially too young, in the TSA agent's opinion, to control the carry-ons is entirely moot, three ticketed passengers with six carry-ons is perfectly within the FAA rules. But I will admit that I believe the number of carry ons allowed to be airline policies rather than FAA rules, and I could be wrong on that point.
Dick Taylor