I would imagine, to some extent, as zapping devices get more sophisticated and users begin to understand that "zappers" can be used for targeting specific ails they greatly threaten the profits of extremely expensive medical devices that work on the same, or similar principles such as Bone Growth Stimulators, tens units and a plethora of others (that for the most part work on a/or batteries).
A small underground movement posses little or no perceived threat to pharmaceutical/medical firms and the FDA so is, for the most part left alone. However if the (zapper) movement picks up steam and begins to go mainstream, there will be FDA/Gov't scare tactics, lies and public arrests engineered to scare (by showing it is dangerous to use, even though it may be identical in application to a marketed device) the general public away from considering self treatment.
I think people are just beginning to clearly see through these profits at all costs (even at the expense of your lives) crap; unfortunately, most people do not yet want to believe it. I run into them every day, their response, "yea, you are right, but what can I do about it?
Similar tactics have already been used in the natural health industry. Look at Ephedra; a few people die (who blatantly abused the herb) and it is banned outright while tens of thousands die every year from prescriptions, through side effects, including suicidal tendancies, and/or miss-application (read abuse like the Ephedra; or incorrect prescribing by the Physician). Short of a catastrophic class action by those harmed (too late to prevent deaths and injury), it is business as usual in selling toxic drugs to unwary consumers.
The FDA cannot afford to let self treating individuals undermine the profits of their bread and butter (the processed food, medical and pharmaceutical industry) otherwise the FDA will be put out of business.