Islamic Banking

As I understand of Banking, it is mainly mere lending of money to people and paid back with interest. Whereas the Islamic bank should be lending money to people without interest because that is prohibited in Islam. Nevertheless, how the Islamic bank can thrive without the interest. Who will invest on such a deal that is without a profit?
The experts say it’s profit-sharing of investors and the borrower, include the operational funding of the banks. There is also ‘risk-taking’ involved this way. Therefore the Muslim investors still resort to conventional capitalist system of banking, though only modified with a minimal interest, which is still a ribah in a strict sense.
In Islam, there is the so-called zakah and sadaqah system (that is, an obligatory and voluntary donation, respectively). In Shia Islam, there is even khums system which is very much the same with zakah and sadaqah but only a bigger amount of money given.
My point is, the Islamic bank should be lending money to poor or needy people so that they can have the capital to put up business or investments to better their lives - without interest. After paying the capital, and the people have made their lives economically and financially capable, they should be giving back the favor done to them by paying zakah/sadaqah/khums to the Bank, which needs funding to finance its operations and further help other needy people.
The bank, of course, should be checking first the viability of the project proposals or feasibility studies submitted by the borrowers to minimize the risks involved. There should be a systematic procedure to ensure that the investments are productive and viable so that the project will not be a failure.
This way, there would be more and more poor people helped and uplifted from their plight and consequently capable of giving donations, and lesser and lesser people would be needing help. Until there would be no more needy and everyone would then be giving zakah/sadaqah/khums to the bank as a funding for any eventuality.
Hence, the bank should be a public/government-operated agency and not supposed to be a private one. Therefore, it should no longer be called a bank anymore but I think it should be called a Treasury (Bayt al-Mal)
Banking should be abolished from the vocabulary of Muslims because there is no use anymore. It would be remembered only as the institution that has made poor poorer, and the rich richer.
Tax should also be mentioned here. Islam is about all aspects of human’s life. And taxation is like banking; it should be abolished and replaced with the Islamic system of zakah/sadaqah/khums.
This is the true Islamic system. There is no such thing as profit-sharing or risk-taking. Only to please Allah.