That’s not how active noise cancelling works. Any difference in sound you may notice is either due to the headphones simply having good padding or due to the noise cancellation making things seem quieter in general because it will be effective at cancelling out the plane’s engines.

Or maybe people shouldn’t bring toddlers on a plane. You don’t need a plane to have a perfectly fine vacation.

Agreed. I don’t have kids and I feel that it’s my responsibility to bring earplugs and headphones if I want a quiet flight.