One thing that I've always found interesting is that, historically speaking, usury is very consistently frowned upon, even across societies that are otherwise very different. What more, the interest limits were usually far harsher than anything that we have today.
One can't help but wonder if our society being so deviant from the historical norm is evidence of its long-term unsustainability.
That's true, but the usury back in the day was usually about loans to individuals. These days, you can bankrupt out of it.
Traditionally, the Catholic Church has made a distinction between loans ultimately backed by an individual's ability to sell their labor for money (mutuum loans), and loans ultimately backed by assets (societas loans).
For societas loans, such as a non-recourse mortgage or a business loan, there is no regulation whatsoever. This is just equivalent to moving property around.
For mutuum loans, these are considered as a form of slavery. If a profit is being made on it, it is illicit. The reason it's slavery is that it allows you to sell your time before you have it. If that money is spent, you are now in a position where you are being forced to work for nothing, i.e. textbook slavery.
One can't help but wonder if our society being so deviant from the historical norm is evidence of its long-term unsustainability.