Due to layout of garden we cant secure entire garden but they have a catio and many indoor shelves - one room has entire walkway around top.
They also get regular walks in rest of the garden. Even in the UK indoors cats do tend to live longer as they avoid external threats like cars other animals.
Many cats die on the roads here - often not the ones people think most dangerous. I personally don't think it's better cat ownership to let a pet die in pain alone on a road - but I do think indoor cats are much more work.