If they are so worried about their compensation, I suggest they go work in South Korea.
American teachers couldn't handle the # of hours the average K-12 Korean teacher has to put in. They have school all year long with a few breaks in between, no 3 month + summer break in the ROK.
The schools are also mostly single-sex schools. Co-ed schools are rare, and even those schools have most of the classes divided by gender. Classroom sizes are also larger, much larger than most American schools (50 students in a class is not unheard of). Study sessions can last until 10 p.m. I don't know of any American teachers teaching study hall until 10 p.m.
EPIK - English Program in Korea - Public School Jobs in Korea
Send these links to the next teacher who complains about how little they get paid compared to Korean teachers. They have larger class sizes and are expected to be excellent and are expected to demand the same from their students.