It certainly seems the outdoors environment and laws are different in the UK and NA. I thought it was a joke when I was in Canada last year and a friend was distraught when their cat slipped outside because it was breaking the law. If any government tried to introduce such a law here, there would be a revolution (I am only half joking - we feel very strongly about our animals here, and it is so off the agenda having 'cat-laws' that I have never heard them spoken of here. Such an idea is completely inconceivable).
And our outdoors does seem much more benign to cats. There are cars, but no predators, no dangerous diseases (fleas is about it), and a nation of cat-addicts. The biggest problem if you let your cat out is pursuading your neighbours not to feed it (this can cause big tug-of-love problems!). My cat Bingo wanders around our neighbours house all the time, and eats their cats' food - but we are all cat lovers and its not been a problem for anyone. There are so many cat lovers in the UK, that there are virtually no feral cats (I've never seen one), and if your cat does get lost and taken to a home, it is very unlikely to be put down - but almost certainly rehoused.
I've had in the past two cats who had total freedom to go outdoors, and both lived fit and healthy lives til they were eighteen years