One does not have to labor hard to convince anyone of the value of saving any surplus for use in the future.

Lending, on the other hand, has always been treated with great suspicion and has in may societies been outright forbidden when it involved charging interest.  This has usually been a recognition of the fact that the lender, from the outset, had a particular advantage over the borrower.  A borrower finding himself or herself in a position of extreme need, would usually be forced to accept extremely disadvantageous terms for the loan.  This inequitable relationship between two parties more likely than not had a propensity to go sour for a number of reasons, not the least of them being the initial perception by both parties as to the dominance/submission nature of the relationship being entered into.