I work at an "international" school in the UAE. Not all "international" schools are equal, some are local schools that provide a curriculum derived from elsewhere. This means that English second language students are force fed through a program equivalent to their native speaking peers in situ. Typically second language speakers are at least 2 years behind their native speaking peers and forcing them through the same material based on age is frankly ludicrous and does not achieve results to anyone's satisfaction with the exception of the private company who hosts the fracas. Parents should be asking why is my ESL child doing the same curriculum as a native speaker of the same age; why am I being charged for access to the IB when my child does not have the competence required and what measures is the school taking to bridge the gap, why am I paying for year 12 IB when the most that can be achieved is lower level certification that students back in program of origin can do in Grade 10.
Essentially what is happening here is that private education is exploiting the naivety of parents and an abundant cash flow.