Assuming a cost of capital of 3%, if they need to charge 70% interest to make a profit then roughly 40% of their loans are defaulting. A 40% default rate means people are using these loans for consumption, not investment. You need better financial education then, not better access to credit.
With competition the rate should go down. Even if it is mainly caused by overhead, as companies will figure out how to operate more efficiently.
Nothing is stopping you from loaning your money at a lower rate, from providing education, etc.
What? You only tell other people what to do with their money? If your advise is not good enough for your money....
If you are interested in this topic you check out my master thesis of 2004 (if you don't mind my crappy English) here: http://www.scribd.com/doc/92714/Microfinance
It covers exactly that topic.