ORIGINAL: pappy35
The reason you must accept interference is so that the Feds (read Department of Defense) don't have to worry about independent designers or companies (or terrorists) desiging and marketing (or utilizing) devices that can't be jammed. Every electronic device of any kind I've ever owned has had that "must accept interference" statement written on it.
Sorry, but the regs state that you must accept interference in the sense that you have to live with it. You can't complain to the FCC about getting interference. You're not allowed to interfere with other systems, but if you get interference, you just have to grin and bear it. If you can build a system that rejects all types of signals but those you want, great! It has nothing to do with DoD requirements or something re: Homeland Security.
72 MHz is the same way. The channels are between those of high-power commercial users. We are not allowed to cause any interference with their operations, but we must accept any interference on our channels. That's because 72 MHz R/C operations are secondary to the other ones. If we get 'hit' by a high-power commercial user, we have no recourse...we must "accept" the interference...grin and bear it, in other words. Again, it's not because "un-hittable" systems may not be designed.
We've had a lot of experience over the years working with the FCC in transmitter certification, and that's what it means when the regs say you must "accept" interference.