Domestic cats should not be let outdoors for a variety of reasons. A friend of mine had a cat which was never allowed outdoors and lived to be 23 years old. Cats who are allowed to roam the outdoors can contract diseases, parasites, fleas and ticks making their life miserable. They can get in fights with other cats over territory resulting in injury, disease, pain or even death. They can and do get hit by cars. They kill garden plants, flowers and grass as they urinate and defecate in prepared soil. They hunt and kill indigenous wildlife such as chipmunks, squirrels and birds. I stopped putting bird seed in my feeder because I was attracting cats and was regularly finding dead birds beneath my deck. One day I noticed that my 15 foot tall Rose of Sharon was vibrating intermittently. I walked up to it to inspect the source of the agitation and there was a cat struggling to climb toward a bird's nest way up in the tenderest of branches. Of course, the number one reason not to let a cat outdoors is that they procreate. Hence, fifteen cats.
I can report that I no longer have 15 cats roaming my neighborhood. One local fluffy was hit by a car and another contracted feline AIDS. Another reason for the wipe out is the increased fox and hawk population (see the attached video I took looking out my back door). It should also be noted that many predators love cat-meat.
There was also a drought this past summer. When people let their cats outside and don't provide a drinking bowl for them, the cat will seek water where they can find it. In the case of two of my neighbors, their pools.
One neighbor found a cat drowned in her pool but she wasn't very lucky a few weeks later when she found the second one. The second cat clawed the lining in an attempt to get out, but failed. My neighbor had to purchase a new and expensive lining for the pool. That cat was her own so she couldn't sue anyone for the damages. Another neighbor found two dead cats in his pool within two days. One of them managed to climb upon a round blowup life preserver but must have popped it with its claws and due to exhaustion eventually sank to its doom expending all nine lives in one evening.
There is an apartment complex near me and I know that the owner was getting complaints of rats and mice around his dumpster. His solution was to put out rat poison. I am not entirely sure what would happen to a cat who consumed a poisoned mouse but, I bet it can't be good.
I was very saddened when I came home one day in June to find a flyer on my door with the picture of a beautiful kitty named "Einstein." He has been missing for a few weeks and the neighbor, two blocks up, wrote "He is very much missed!!!!! Please call."
Any veterinarian will tell you that an indoor car will live much longer and healthier than an outdoor cat. I wonder why. I bet that Einstein knows the fate which befalls frisky, footloose and unfettered fancy free feline.