Buddy - banks lend a LOT of money at 15% and more (have you heard of Credit cards as just one example?).
Which is why WM did not go to McBank for debt funding. Business loans attract high interest because of risk, and loans from the big boys in the USA are commonly above 15%.
Just because Commonwealth advertises 6.85% for $100,000@ 3 years doesnt mean that is the end of it. $100m is entirely a different matter.