Re: so the monitors are susceptible?
Because the majority of tests are to ensure the equipment does not cause interference rather than cannot be interfered with.
most electrical gear ends up with the usual FCC statement on it in addition to other marks for different regions. The bit in (2) spells out where the problem lies.
This device complies with part 15 of the FCC rules. Operation is subject to the following two conditions: (1) This device may not cause harmful interference, and (2) this device must accept any interference received, including interference that may cause undesired operation.