Banks don't necessarily borrow at 0%. Granted, they are able to borrow at a much lower rate than you or me (closer to the Federal Funds Rate managed by the U.S. Federal Reserve), but they still pay interest on their loans.
Of course, real interest rates have gotten close to zero, but in general real interest rates of 0% are nonsensical in stable, developed economies. Economically speaking, if rates were 0%, it would in the long run make sense to bulldoze the rocky mountains to save money on gas, because there is no marginal cost to consider.
Of course, real interest rates have gotten close to zero, but in general real interest rates of 0% are nonsensical in stable, developed economies. Economically speaking, if rates were 0%, it would in the long run make sense to bulldoze the rocky mountains to save money on gas, because there is no marginal cost to consider.