Terrorism finance is a very complex subject which I'm only peripherally knowledgeable about. I'm sure they know it's happening, but they're just not able or willing to address it. Wahabism is a very strict and intolerant ideology to start with, so preaching things we might consider unacceptable are quite acceptable to them. The problem from their point of view is much smaller than it is from ours.

However where the ideology being supported and promulgated does go beyond what they would consider acceptable, they just don't have and are basically incapable of the level of oversight and monitoring required to identify and address it. That occurs to far down the funding and management chain for them to be equipped to deal with it. So in reality their choices are switch off the whole thing - billions of dollars in funding for education, health and charitable causes across the Muslim world on which extensive programmes and hundreds of thousands livelihoods depend - or live with the downside while making ineffectual efforts to control it. From their point of view these programmes are doing vastly more good than harm. It's just a matter of relative priorities.