Outdoor cats do a lot of damage to gardens around here. They also kill protected species of birds. That is why there is a local ordinance here. Let your untagged kitty roam and it will go to the pound and eventually will be destroyed. Tagged kitties that get picked up will mean you pay a fine to get it back. If you love your pet cat you will never let it roam becsuse it could be killed by dogs or other cats or it could get hit by a car.
The safety issue depends a lot on where you live. At my suburban home, it’s pretty safe. Only one of my cats has ever been hit by a car and he was 15 years old, slowing down, and simply refused to spend any time inside except to eat. He had a good long life, and died quickly, doing what he loved to do. Lost one last year at age 21 to a pulmonary embolism — he’d enjoyed roaming outdoors his whole life, right up to the day before he died. Another had to be put to sleep at age 19ish due to heart and liver failure, and he’d enjoyed the outdoors for the 3.5 years since I’d adopted him from a shelter.
We scatter bird seen in the driveway every day, and have a little pond/fountain most of the year, replaced by an electric-warmed water bowl in the winter. My bird population is definitely thriving. Once in a while, one of the cats gets a bird, but any of my cats who shows serious interest and aptitude for bird-catching is quickly outfitted with a loud collar-bell, which puts a stop to catchings of any but old or sick birds.
That’s what I’ve always told cat people. What kind of favor are you doing to your cat by letting him go free? They get in fights with other cats, wild animals (maybe pick up diseases they wouldn’t get if they were indoors), dogs can come after them, cars can hit them, etc.
Plus, I have been told by plenty of cat owners (I am not a cat owner), that if you NEVER let your cat outside to begin with, it will be just fine being an indoor cat. They said their cats generally do not want to go outside, they like being an indoor animal.