In terms of regular or anticipated natural disasters, the UK has it pretty tame. There's flooding to worry about, and that's pretty much it. On the other hand much of the US and Canada is either in an earthquake zone, or gets regular hurricanes, both of which can knock natural gas (as pointed out by GP). And many backup generator scenarios cannot be solved by a second site outside the disaster area. Hospitals come to mind immediately, and I know someone who's condo uses a backup generator for emergency power.