@mathanxiety like I said it’s shared. I know it might not be what you’d want in your own garden, but unless it’s explicitly prohibited in the lease or elsewhere, it’s just tough - that’s the nature of shared spaces.
Sharing means you don’t get to dictate how others use the space, unless this is set out in deeds, leaseholds etc.
One person might not want a dog in the garden, another might not want the neighbour to hog the whole garden by having a bbq with friends, or whatever, but unless there’s a specific rule against it, it’s just hard luck. Assuming no rules in place, you can’t tell one person they can’t allow their dog into the garden anymore than they can tell you that you shouldn’t have a bbq in the garden.
That’s not to say I don’t think everyone should be kind, considerate and respectful. I completely think it’s good manners to be considerate of how you use a shared space, but that applies to everyone - whether it’s cleaning up after the dog, letting your neighbours know you’ll be using the garden for a party, not leaving rubbish out in the space, and so on.
I understand some people don’t like dogs, but if you really don’t like them, don’t move somewhere with a shared garden, or only live somewhere where dogs aren’t allowed or are prohibited from doing the things you don’t like.