PW - surprisingly many of them compete very effectively in an open market because they have vastly lower wage costs (for now at least). You only have to look at the recent successes of countries like China and Indonesia and indeed India to see that. Manufacturing will probably continue to drift to developing countries for the next 10 years or so, at which point there will be a levelling out of the cheaper wage costs.
The fact is though that there the developing world is hugely dependent on the developed world for trade and yes, that puts them at a disadvantage in negotiating position. However, do not assume it is by any means a push over. One only has to try and do business with China, for example, to see how incredibly switched on they are and how they drive a very hard bargain indeed.
The banks are in any case, mostly global enterprises these days and are actually encouraged quite strongly to work with the developing world who need credit is huge amounts, to invest in infrastructure to get factories etc off the ground. On the flip side, banks write off billions and billions of debts from the developing world at the moment. I'm not saying they are acting altruistically at all, but one can;t help feeling that they are working on very low margins in the present environment, in the hope of making much more money in the future once the economies are more solid.
The point about corruption is that in countries where it is most prevalent, almost nothing can be done to better the lives of those who live there. As such, it is probably the biggest barrier to development in those countries. The problem with multi-nationals and banking is somewhat different, it is that development might happen too quickly and in ways which does not support the long term success of the countries in question. Although, there has been a major shift away from this type of behaviour in recent years, not least because most have switched to an ethos of employing local senior management only, which usually means that the needs of the local populations are not overlooked entirely. That always supposes that you don't end up with the local bent businessman running the show!