The Exit Row Instructions are derived from FAA regulations and federal law; they’re uniform across US airlines and essentially the same on domestic airlines in Canada, Australia, and UK.
Years ago United Airlines seated my six-year-old grandson by the exit door. He was traveling with his parents but they were seated elsewhere. They got him moved - seriously, a six-year-old is going to help other passengers get off? My family never flew United again. It was a long flight, from Seattle to Germany.