I Agree with you all the way. But like you said, realities are very different. capitalism has its way through people's stomach. It works on pay on need basis, and not on ""SHOULDS"' or religious books.
Marxism) works on human ( Socialism) basis, but then it becomes poor, exploited and corrupt by people on top. Hence masses also become poor and unproductive. It failed miserably around the globe.
At present or in history, i am not aware of any islamic region ever adopted Quranic principals for their Economical structure ( may be earlier times of Barter or gold exchange). . But then many scholars believe that Capitalism is also Quranic way, it just need to be monitored on just basis. Thats why it proved successful around the world and continuing. You earn what you do.
It is unfortunate that since centuries, mulsim scholars are counting the evils of Interest system, How UnQuranic it is, but so far none has presented a real Quranic , workable, viable and acceptable by international community. Muslims have to live with the world, they can not have their own world, and for that it has to be compatible with current international finance systems. Some institution came up with different names of Interest system as Islamic, but they were all self deceiving. Some solutions are limited to books and articles only.
World lives on commodities exchange Import export, which only works on banking interests. No banks no exchange. No cell phone, no rice.
Wishes are great but are not solutions. The only viable, probable solution could be that entire Muslim Countries Finance Ministers, experts and bankers work to come up with some thing. Even it takes years, it will be worth a shot. Other wise Mullahs will keep giving sermons in the next centuries.
If United Nations (UNO) can be developed and it is good in many affairs, the why not an Islamic nations Organisations (INO). There is OIC, but so far it has proved to be an impotent entity, good for conferences only.