It's because American technology is generally stone age. The Germans actually can build something that works, when we do something right it runs out of money (I.E. Beagle).
Ford is skint, so they have to. But if that technology that is being shared works, it's not as if there is a problem.
It's not like BL where there was no joined up thinking at all (what killed it). The problem with British Leyland was the only thing they did was share dealers.
Let's choose the worst example of sheer lunacy - the Triumph Stag. It's main rival was BL stablemate, the MG B.
Rover, another arm of BL, had bought the rights to the absolute mutt's nuts Buick V8. We all know about that. But what engine did Triumph stick in the stag? They didn't go for the all-aluminium light as a feather unit. Oh no. They got two inline fours and practically stuck them together with parcel tape. Silly idea, crap engine. Technology sharing works.
Don't underestimate TATA. They have more than capable people - they produce similar levels of cars to Subaru. OK, they produce cheaper cars but I feel sure they should be capable. It's not as if Ford didn't do cheap and nasty. TATA should do a good job.
As for the production, I don't care if they start producing the cars in India or not. They are a company, not a bloody job creation scheme. They don't have plans to move production. They won't move R and D, they know they just won't be able to do it in India.
Is there any large British motor manufacturer? No. David Richards lead a consortium to by Aston Martin, but they produce less cars in a year than either of those make in a week.