Odd, I don't see a tow weight rating in the Q30 owner's manual but they mention towing and give you tips on how to do so safely. Not sure if the Q30 was meant for towing or not, or how much weight it can bear.
Often you can push the limit a bit, but when doing that you also have to be mindful of how you drive... so using lower gears off the line and going on an incline, things like that usually position you better than those that don't think it through.
That might be solely due to regulation. Don't know anything about the UK market (if anyone does enlighten us, please), but for all we know their regulations could be quite lax and not as tight as they're known to be in the U.S.
At least when we (Americans) get something odds are its **** good.
Not too sure about the differences either other than their fuel standards but I can't see why they would have them on the UK side and not the US side. Here in the US tow hooks are definitely extremely desirable.