Leonie - maybe it would help if you accept that no one makes infant feeding decisions in a cultural vacuum. We are all the products of our society, culture, family and experiences. That doesn't mean we cannot have any autonomy in what we do, but that autonomy comes with maturity and self-awareness and how many people have that in abundance at 17 (or even 70 in some cases)?
When people make a deliberate choice to ff, they are not being lazy or selfish (well, I suppose some individuals are, seeing as how the human race has all sorts). They love and want the best for their babies. But they don't feel that the effort to breastfeed - to go against cultural and social expectations , which is an effort - is worth it, because they don't see it makes much difference.
They might accept in their heads that 'breast is best' (horrible phrase) but what they really believe is 'breast is probably a bit better than formula, I suppose, but not enough to make a difference, and anyway formula is better because......' Insert arguments of your choice, including the rubbish we see here, sometimes, like the mother's diet means her milk is crap, or she smokes, or whatever. Plus the other stuff about other people being able to feed the baby, you can see how much he's getting and so on (these last are true, but they don't make formula 'better').
Then there are people with body issues - they love and want the best for their babies, but they cannot ever feel comfortable about using their own bodies for this purpose. Think about the tyranny of the body (and food) on women - and how breastfeeding combines these two tyrannies but with another person involved, too. Analyse that :) :)
Add to the mix women who might have a history of abuse that involved their breasts - yes, it could be healing to breastfeed, and I know personally of cases where breastfeeding really does help body/sex/food issues, but you need that maturity and insight and a desire to tackle the problems first.
So where does 'lazy and selfish' come in? Nowhere.