Keeping to the sueing over cheese analogy, there would be a host of people with partial 'responsibility' for serving the cheese though, the woman ordering it, the waiter, the chef, the owner, whoever devised the menu etc whereas with a tattoo, the buck stops with the tattooist so perhaps it is just that they are more mindful of the potential consequences for them personally and professionally.
You are of course right about my lumping drunken consent in with pregnancy as being wrong, that was lazy posting on my part for which I apologise. I think the point i was trying badly to make was that with someone who was drunk, there is a greater risk of bleeding more just as there is during pregnancy, and that a drunk person may be unduly affected by a decision made when under the influence, whilst a nursing infant may be unduly affected by a decision they had no say in so where the lines are a little blurred it is easy to see why blanket ban policies are put in place.
I accept that my viewpoint may be skewed by my opinion on tattoos though, which is that personally I like them (I have 2 and am working on a design for a third) but I believe that they are a big decision and so should be thought on long and hard. That being the case, I don't see it as being such a big deal to wait an extra couple of months to have something done if you have already waited a year to make sure it is the right choice for you, if that couple of months wait totally eradicated any risk to someone else.
I have also realised while posting that that my views seem to mostly centre around breast feeding mothers, rather than pregnant ones, as my view seems skewed by the tattoo potentially affecting another person who is a separate entity to the mother rather than something which is still part of her body. With pregnancy, my issue (for myself, it is up to others what they do for themselves) is more cents around the physical changes pregnancy brings that make tattoos less suitable during that time.