edam, I think you need to consider that you and your dh/p are joint parents, neither has more right that the other over your children.
Just because you know you and your dh are in agreement, doesn't mean anybody else knows it. They need to ask/ see proof if those are the requirements of that country.
And yes, it could be got round, but it would come out pretty damn quick that they had forged permission...not a good look when trying to claim innocence of child abduction.
Its a step in the right direction. Some might see it as officiousness or being a jobsworth, but if you are the parent of a child abducted by another parent, you would go down on your knees thanking them for not believing some shitbag's story of taking their kids for a holiday.
If that means that you and I have to carry a couple more bits of paper, then thats fine by me.
As I said before, I try not to think about what might happen if exp decided to take ds back to his home country and keep him there. I am only thankful he comes from Canada, who are so strict on it. So I am prepared to let him go on that basis. (not that I think there is any risk, but you just never know what goes on in people's heads).
And that is without looking at the whole appalling issue of child trafficking. Victoria Cliembe was brought to this country by her "aunt". Maybe a little more rigour might have averted the tragedy of that child's life.