There is a simple reason why the UCP promotes charter schools over the public school system. Charter schools are not governed by elected school boards, and they do not have to be unionized. Alberta remains the only province in Canada that allows charter schools.
https://www.sprawlcalgary.com/bill-28-school-land-developer-offsite-levies
#ABpoli
UCP to make public land available to charter schools with Bill 28 | The Sprawl

Developers will also pay less in off-site levies.

The Sprawl