What does a better behaved baby mean ? One that sits around/sleeps silently and is too POLITE to wake his parents to be fed/cuddled 
I remember my own female GP recommending "just the one" bottle at night when I told her I was exhausted and in constant pain (I had severe pelvic pain after a very long natural birth and couldn't sit on my bottom properly for 6 months after DS's birth). She actually said "you will be able to get away with just the one".
At this stage my son was only one week old, had only just started to latch on properly and thriving on EBF. I had to do my own BF research to discover that it was the worst advice one could possibly give a woman keen on EBF for a long period of time.
DS was never formula fed as I chose to disregard such advice. The solution to my pain was BF on my side on a bed, lying down next to DS. I used to even ask to go into friend's bedrooms to feed DS when we were out as lying down was the only thing we could do comfortably.
Breastfeeding a fussy baby (he woke up every hour for the first nine months of his life) like my own and suffering pelvic pain at the same time, was catagorically NOT an easy task. However, I am very probably an isolated case and I would say that in most instances woman who stick to EBF do not have difficulties.
In fact looking at international research around the world, I would say that low BF rates in the UK are not due to the fact that we have "more difficult" babies (that would defy scientific logic).
EBF (and length of BF after 6 months) has as much to do with culture, tradition and the availabilty of GOOD BF advice as anything else.