On many systems, a dynamic or a condenser mic will work, depending on the auto-gain range of the mic pre-amp, or in cases where both mic pre-amps are available and are auto-switched by the audio system. The impedance of the mic itself can trigger the selection if the designer wanted it to.
Dynamic mics need a LOT more amplification because their typical output signal is around 10mV or less, whereas a condenser mic, which usually has a small single transistor "amp" inside, can produce 100mV signals or more (the line power not only charges the capacitive 'condenser' but also can provide a current source for the FET pre-amp transistor.
At any rate, you're right to a degree: my headsets work great with the Garmin Zumo, the J&M CB2003, and many BMW systems, regardless of what company technicians may say otherwise, it's not really rocket science. My sets also work with many other systems that are technically designed for condenser mics, but some BMW owners have told me the mics won't work at all on their bikes, and some tell me they love the sound. Hence, some testing is in order to see what's different on the bikes.
Appreciate the feedback ... a poor choice of words when discussing microphones...