The only segment where BYO phone is strong is in prepaid. You do actually save money by not being on a plan but this isn't the option most people go for. People don't see it as the "grown-up" option.
Not many people do you think buy an iphone from Apple for $1040(http://store.apple.com/au/browse/home/shop_iphone/family/iph...). They get it from Optus or something for $10 p/m or free. http://personal.optus.com.au/web/ocaportal.portal?_nfpb=true...
Again, yes, in the US. In some Asian countries, you can walk into any mall and there will be any number of stores selling new or used cellphones all of which are unlocked.
> People don't see it as the "grown up" option.
Again, this is limited to particular cultures. In some countries, prepaid is the norm, not the exception. People keep their numbers and switch phones as they move from one phone to the next, and buy only as much load as they need. (USD 0.20 good for 10 SMS messages)
We still need number portability and affordable mobile Internet, though. Ah well.
EDIT: s/India/New Delhi. I'm not sure about the state of mobile networks in other parts of the country.
But yes for instance in France it's like that: permanent exclusivity is illegal, though short temporary ones are allowed. Orange (illegal) exclusivity on the iPhone was broken in April 2009 and since then all operators are selling it.
Consequence : 2 million iPhones sold in 2009, more than 50% of the smartphone market shares, and 3G networks that have a hard time following the pace...
They've done it for years, but not in the US.
http://shop.nokia.co.uk/nokia-uk/searchresults.aspx?search_i...
http://store.nokia.com/webapp/wcs/stores/servlet/shophome_10...