Of the countries I've flown in with my almost-2-year-old:
US - pretty much ignore your existence (shocker, I know)
Canada - Give you a briefing each flight on exactly how to hold your child and a personal reminder about the oxygen mask rule
Australia - seat belt extender
TBH, I'm not really sure what the seat belt extender accomplishes. I tried seeing how much my baby would move with both mine and his at the tightest possible. He easily smacked into the seat in front of me.