I think you are correct, it is just that it is actually required that you do charge interest.
However, I worked with a woman who was Jewish. She showed up in a new car one day and we went for a ride.
I asked her how and when she went and got the car.
She said "oh I got a loan from the Jewish community" or something to that effect.
I inquired what that meant; she said that she was able to get a loan from some Jewish social circle and she didn't have to pay interest because she needed someone else from the Jewish circle who was willing to back her and pay the loan of she failed to pay.
I didn't ask what the consequences were if she failed to pay - but she just mentioned that "if you know Jewish people... Getting money isn't hard"