Is 'poker' specifically the issue here because you are not playing against the house and you are playing a game of 'skill' rather than 'chance'?

I remember when the tax laws changed here years ago there were long running debates over which forms of gambling were skill or chance.

Did you know that in the UK you are permitted to have a licence for 'public gaming' for your own house for one day a year.. due to some 300 year old law that never got repealed