God this is getting circular!
Earlier I added a comment that many supermarket curries actually ARE BIRs. As I said the Mumtaz restaurant supplies Morrisons and ASDA I am sure.
And the mass production argument is a bit fallacious: if you are looking for a homemade version of a takeaway, the hardest thing is scaling down to a few portions a process designed to throw out a couple of hundred covers a night - and therein lies the issue.
Personally I am rapidly coming to the conclusion that if I want a restaurant style curry, I go to a restaurant. If I want to cook it myself I get homestyle curry. Not an issue really. And if I can't get to the takeaway I have a freezer full of BIR curries thanks to ASDA.
Incidentally I have a Goan Goddaughter. Having been there to visit many times not one single dish I have been served by my family out there has the slightest resemblance to anything you get in a BIR. It is still, however, delicious. (And usually too hot)
Mike