I don’t understand you differentiating between Public and Thai.
You say local school. That could mean anything from local village school to largest school in town, depending where you live.
My daughter attended Anuban Buriram. Most if not all main towns will have a school named Anuban + Town/District name. They are government schools and all teach the same curriculum. Great schools too. In 9 years my daughter was there, kindergarten to P6, I only ever had one cause to complain.
Fees were in the region of 3k per term. General study was free. Payments for computers, learning with foreign teacher, food and insurance.
Sounds like you are sending your kid to a private school (public in England). As one other poster commented, often in Thailand paying high fees doesn't mean better school.