wellie - you say : "IMO there's no evolutionary pressure for BF to be painless, because until very recently (iin evolutionary terms) if you didn't BF your baby would starve, so presumably everyone would have just got on with it".
Yes you have said it. In the days when formula was NOT readily available/relatively affordable, then women HAD to bf no matter what the pain, short-term or long-term, etc. you either did it or your baby literally starved.
I had that attitude when I started to bf. I put the fact that formula exists out of my mind, I pretended it didn't exist. That way I made sure I just got on with it, even though I had excrutiating pain (we got thrush at 3 months) and many other problems along the way. My baby could have "starved" as he would not latch for the first 4 days after birth and no one bothered to tell me it may have been because he was born 17 days early. I persisted and eventually he latched.
If women feel they are being "bullied" into bf, one has to look at the underlying social structure that makes them feel that way in a country that is in fact totally dominated by formula.
I was certainly never bullied into trying ff (never did try it) but the snide remarks from all and sundry would have been enough to make a less confident woman question herself and give up altogether.
The so-called bullying and pressure happens whether you bf or ff. It is a fact of our culture and a telling detail of how crap women are still treated despite decades of "feminism".