Maybe if public schools competed with private and charter schools on a level field, they would not be concerned. The field is not level.
Private schools rarely claim to play by the same rules as public schools, but charter schools often claim they are open to any student, regardless of ability. That may be true, but there are still differences.
Charter schools, like private schools, are populated by students who, along with their parents, care enough to investigate their educational options. That effort alone sets those students apart from the average kid whose parents just send him/her to whichever school is closest.
Also, charter/private schools usually have requirements for attendance that public schools cannot have. These requirements may include mandatory tutoring sessions and active parent involvement.
Let me give three examples of the differences between public schools and private or charter schools. Ben was a wrestler at a Catholic high school. When he transferred to the school where I taught, he wound up in my algebra class. I was the wrestling coach and wanted to get him out for my team, but he didn’t stay academically eligible.
When I spoke to his old wrestling coach at the private school, I was told he was kicked out of that school for failing to do his homework. Public schools would perform much better in standardized testing if we could kick out the kids who don’t do their homework.
Rob transferred to my school from a private school. He was a struggling, hard-working student in one of my classes. He was also a member of our track and cross-country teams.
When I mentioned to the athletic director at his former, private school that I thought Rob was a great kid and a hard worker, I was told that his former coaches hated to lose him, but that he couldn’t “cut it” there academically and was advised to transfer.
The district where I taught had a charter school that is often on lists of the best high schools in the country. Admission is by lottery. However, if a student can’t keep up with the rigorous curriculum, the parents are simply told that they should look for “a more appropriate setting” for their child.
When comparing regular public schools with charter schools or private schools, keep in mind that public schools do not have the option to send away kids who choose to not work hard, who struggle academically or who have behavioral problems.