Namaste,
Aap kaisi ho ? How are you ?
It's very interesting Q.
I appreciate, more than Q it's your observation.
See, In movies, actually they should in pure /native Hindi. But they don't follow that. Producers / directors look at movies just to give entertainment. IN the process (wrongly) they mix up Hindi + English = HINGLISH. Futhermore, now-a-days it's a trend to speak hindi with foreign words. (which is absurd) However, considering Entertainment angle, movies are enjoyable, isn't ?
In a way, U R right, Britishers ruled over India for quite a long time, It's British English's impact and not American accent.
By the way, Have U watched Munnaa bhaaee MBBS ?
DHANAYWAAD,