Why is it hard?I know a lot of people that don't allow dogs at gatherings though, simply because if one person brings a dog, even a very well behaved one, it's hard to tell others not bring dogs even not very well behaved ones.
Dog misbehaves = Dog banned. Dog behaves = Dog welcomed back.
I don't think it's hard. IMO, people just don't want to do the work so they just ban everything instead of taking dogs as the individuals that they are and judging their behavior accordingly.