I assume they have data for other devices as well, although the FCC proposal doesn't list it. Since the call centers are the ones asking for this change (no the phone companies), it's probably because this category of devices is an outlier for them and the problem they pose is much higher than other call sources. The call centers have no financial interest in the sources of the calls the get. Their financial interests are in resource allocation for incoming calls and costs associated with unnecessary and fraudulent calls. I'm sure you could make a few inquiries and get the numbers from some of the agencies mentioned in the FCC proposal.