This is crated again by those radical Islamic groups. Many countries have such a power but can't do anything against those groups. Cut their income, find their sources of income and just cut it. It is so simple but i know it is a big task. Nothing can exist without income.
You're right, it IS simple. Why don't they do it? Governments don't care enough? No. Governments don't have enough incentive? Possibly. Governments are bought by these organizations? Likely!
Why do you think the country of United Arab Emirates flourished (like, literally became relevant) in the first decade of the 2000s while Osama bin Laden was running amok around the Middle East and elsewhere? Because the UAE said stay the fuck out of our yard! The UAE probably donated to his cause in return for him backing the f-off of their attempt to embrace some capitalism and the wealth that comes with it.
