They do: https://www.cbc.ca/news/canada/toronto/porter-airlines-flight-to-toronto-cancelled-child-standing-on-seat-9.7300786

I’ve always seen the flight attendants stand and wait until whatever they request has been adjusted. But 90% of my flying experience is in Europe so maybe it’s different in the US.

Even friggin breakfast had to wait.

Come on guys, they said you were well-seasoned.

(started singing this as a lullaby for my kid… nothing calms kids like tales of storms and death, the Grimm brothers taught me that)