Comment by woodpanel

It's becoming fashionable outside the US as well. And the core reason is that public schools deteriorate.

Public school systems sucks at diversity. It demands parents and students to endure diversity (i.e. putting kids from all walks of life into a single class), while it delivers zero itself, i.e. refusing to diversify its offerings as affluent kids from high-iq parents need different schooling than the fresh foreign refugee-arrival from a war-torn country.

Teachers Unions make sure to deflct any "market pressure" from teachers and these unions' political arms (i.e. left-leaning progressive parties) rake in extra profits because they can cry wolf about the bad state of education or worsening abilities for poorer people to rise through the ranks via merit. Crocodile Tears.