While there is a hint of truth in this, there are many middle-class and single income families that choose private schools for a variety of reasons.
More focus on academics vs ideology
Many parents just want their kids to go to school for the academics and social activity; however, there is a growing trend in North America where teachers are highly ideological and use their influence to frame the students' worldview. Parents instead want their children to learn how to think, not what to think. Alberta Teachers in particular, are open leftists in their politics and are quite willing and ready to influence students to follow their lead. In many cases parents feel that teachers do not accurately represent conservative beliefs and create a very one-sided environment. This may not only unduly influence those students to lean and vote left, but also leaves students who have a different worldview feeling ostracized or afraid to voice disagreement to the teacher or other students.
More parental involvement & choice
Many private schools naturally create a family-oriented community around them. This can sometimes be because the schools are smaller, but can often be as a result of the school using parents and volunteers to get more involved in events or school projects. Parents who feel connected to the school are more likely to contribute to their kids' education and support the teachers
Low tolerance for negative behavior
I'll be fair here, there isn't much a Public School can do these days when students don't want to be there. Private schools really do have an unfair advantage since parents and students have "skin in the game" when it comes to paying for private school. As family dynamics break down in our society this problem is only going to get worse in Public Schools and it isn't their fault when they don't have support from the parents and the school system does not allow virtually any kind of discipline. Many teachers have given up on even trying to control their classroom to the point where kids can simply assault each other without any intervention (from personal experience), God bless the teachers who have a gift in this area.
School Uniforms (safety, bullying, focus)
What else needs to be said here? Inappropriate clothing, peer pressure, and bullying are all giant problems in public schools and, to a lesser degree, in Private schools, generally due in part to school uniforms.
