Some of this spectrum interference can be avoided with a combination of directional antennas and modified routing protocols that take a "web of trust" approach to whom can participate in the mesh. But the long-term answer to these concerns is to design your network as a "Cognitive Mesh".
Cognitive Mesh uses "intelligent" router nodes, which can sense which frequencies around it are currently congested or being blocked, and switch the frequency they use accordingly. This technology is very experimental and under world-wide, active research- but it could make large-scale wireless networks very fast, highly reliable, and simultaneously almost impossible to destroy through interference.
This excerpt is from a Dr. Honggang Zhang's laboratory, which researches green wireless technologies and cognitive mesh networks-
"As the radio spectrum usage paradigm moves from the traditional command-and-control allocation scheme to the open spectrum allocation & access scheme, wireless networks meet new opportunities and challenges. Accordingly, we introduce the concept of cognitive wireless mesh networking (CogMesh) and address the unique problems in such a dynamically networking environment. Basically, CogMesh is a self-organized distributed network architecture combining cognitive wireless access technologies (e.g. Cognitive Radio) with the mesh (ad-hoc) structure in order to provide an integrated & converged service platform over a wide range of heterogeneous networks." - Honggang Zhang's laboratory at Zhejiang University
As this description notes, cognitive mesh networks basically combine 2 technologies, Cognitive radio and Wireless Mesh, into a single seamless integration. It is necessary from a commercial perspective, in order to provide very large-scale mesh networks where many people are sharing the same channel frequencies. And it is also necessary to prevent disruption by authoritarian regimes wishing to shut-down free speech and stifle protesters.
Therefore, the use of cognitive mesh networks, particularly cognitive mesh networks with Wi-Fi, is a means by which to create a robust, grassroots technology of direct peer-to-peer communication that cannot be easily shut down by repressive governments.