misd-agin
You are correct in your neck of the woods as
"When cleared to "fly or maintain runway heading", pilots are expected to FLY THE RUNWAY HEADING WITH NO DRIFT CORRECTION applied. AIM PCG R-5"
as my last airline pre-retirement advised its pilots.
However, in other parts of the world it is the norm to maintain runway track.
Just another one of those things that international crews have to be aware of - along with things like the US phraseology 'maintain FL240' meaning 'descend FL240' as per 90% of the rest of the world.
Hey ho