Why are low frequency channels (10kHz - 200kHz) especially susceptible to interference?
If one is trying to send a 10kbit/second data stream modulated at 910.0MHz, the information for every bit of data will be spread out over 91,000 cycle.  By contrast, if one were trying to send a 1kbit/second data stream modulated at 100kHz, each bit of data would be spread out over only 10 cycles.  A lot of radio interference comes from events like the closing and opening of switches that start and stop significant currents.  Each such event may be modeled as clobbering a cycle's worth of communication on all frequencies.  At 910MHz, an event which clobbers one cycle's worth of communication would probably go unnoticed, but at 100kHz, it's far more significant.  It wouldn't take very many such events happening close together to disrupt a bit on a 100kHz-modulated data stream.