Cats are not domesticated, this is your problem, right there.
Sure, they're partially domesticated, but that's only if they're handled by humans during a really quite short period of their time as a kitten. This is why farm cats are feral and generally will not tolerate humans to get near them let alone touch them, the same for other feral populations.
As such they're pretty much a wild animal, with a lot of the same behaviours as their ancestors, if they are kept housebound then they cannot exhibit these natural behaviours. I've seen it with 'friends' cats that are not allowed out. "Oh, he goes crazy and pounces us as we walk past." "You should see him racing around the house climbing the walls, I have no idea why." This is because it can't roam, can't hunt, can't do anything it normally would, so it reverts to , in some cases quite destructive, stereotypic behaviour. This barely falls short of animal cruelty in my eyes. Cats are predators, to them hunting is as instinctive as breathing or breeding.
Sadly, this also means they'll crap in your garden, this fate was sealed probably when the first person found some kittens and thought something along the lines of "the wild buggers eat the mice that raid our grain, if we keep these they'll do the job so much better". Leading to the near domestication we see today.
It's not dissimilar to hating beaver for flooding large areas as it builds its home. Get the supersoaker, fill it with dye, and take satisfaction that they'll merely find someone else's garden to crap in, while possibly scaring the crap out of their owner, who may keep it inside after a while, and thus destroy the cats quality of life.