> profit-loss sharing
We have a term for this, it is called “equity financing.” The alternative is called “debt financing.” Islamic orthodoxy effectively banishes debt financing (unless done at zero interest), while offering equity financing as the solution. But it is not a solution at all.
Suppose that I need to purchase a vehicle, in order to drive to work every day (let’s say I live in a country where public transportation is non-existent, e.g. Saudi Arabia). Without a vehicle, I cannot earn a living. However, to purchase a car I need a large amount of cash, which most people don’t have. The normal solution is debt, i.e. borrow money to finance the purchase of a vehicle, and pay back the lender over time with interest. Everyone wins.
But ... Islam forbids such a transaction. Under true Sharia law, I need to either find a lender who is willing to offer me a zero interest loan so I can buy a car, or I need to find someone who is willing to enter into a “profit/loss sharing” arrangement (whatever that means).
Now nobody is willing to lend money for free (especially not oil rich Islamists who oppose non-Sharia Finance). There are a couple reasons why nobody lends money for free (time value of money, credit risk), but it should be quite obvious that no one will lend me money at zero interest to buy a car.
What about “profit/loss sharing?” Well, I do use the car to earn money (by driving to work). It would be wonderful if we could all pay x% of my monthly salary as a car payment. That means if I earn less, I pay less for my car. If I lose my job, I don’t have to pay anything. If I earn more, I pay more for car payments (for the same car). This has some very obvious problems. It might be good for some consumers who have a modest income, but wealthy consumers would not like this. Moreover, no lender would ever be willing to enter into such an arrangement. It’s completely unworkable. You can say the same for other personal loans, like mortgages and student loans.
So what actually happens in “Sharia Compliant Banking” is that Islamic banks lend money at a fixed rate of interest (just like conventional banks) but they disguise the interest using combinations of legal instruments. Christians in medieval Europe did something very similar (see https://en.m.wikipedia.org/wiki/Contractum_trinius). One consequence of this legal gymnastics is that Islamic bank consumers have fewer legal protections. For example, an “Islamic mortgage” requires you to hand over title of your house to the Islamic bank. This is different and less advantageous to a conventional mortgage where you retain the title to your property.