Translation:Can I get this watch?
Agreed. Why. This was 2 years ago and still this is not accepted. The Japanese sentence does do give us all of the information we need to be able to translate to "Can I get this watch?. Different situations would produce slighty different sentences. I should not be restricted to this sentence alone !
I agree that it's not the best answer, but it is certainly used, apparently even in the UK. It's similar to the "can I?" versus "may I?" debate, where both should be accepted but obviously "may I?" is more correct and should be the top answer. That doesn't invalidate the usage of "can I?"