I think they were very rare even before the laws. I mean first of all it has to be physically possible (I have no idea how a giantress and a human... nevermind) they have to be compatible ("cross breeding" is often impossible in the real world. Genetics are too different which is why you could e.g. not mate a horse with a monkey but a horse with a donkey even though the offspring often is infertile at best) so the species have to be close enough to allow fertilisation and birthing.
Then there's the social stigma, you can bet it's not socially accepted to have a partner from another species.