The AI is much smarter about accepting loans.
You can make 100d loans at 10%, for example. However, I have yet to have a single AI nation accept more than 200d (total) in loans. And not all the AI countries will accept loans. In fact, it seems to be first based on their need for money. Second on their ability to pay back the loan. And lastly, on relations--with a twist.
Some countries will not accpet loans from me. These countries are either in a hostile alliance (i.e. our alliance just got done with a war) or some other factors which I have yet to figure out.