It's not only The UK that is getting ripped off with these offer's... Canadian's don't get those rich welcome bonus deals either.
Example:
The new TD AAdvantage Visa only awards 10,000 points compared to 20,000 for USA.
Chase just introduced a new Marriott credit card in Canada with a very low 5,000 welcome bonus

In The USA they get 15,000 points and a FREE night!