Hair is a poor electrical conductor because its cells are dead. To send enough current down a hair to reach and cauterize its root from the outer end of the hair would require so much power that there would be a risk of burning or even electrocution. To be safe enough to market domestically, home electrolysis tweezer kits must use minuscule power. By the time it has reached the inner end of the hair, the power is negligible and what exists is rapidly dissipared in the surrounding surface skin (epidermis) outside the follicle. Methods using conductive gel share these conditions.

For a report on the results of hair conductivity tests click here (external link). 

These are typically just an MN1604 (PP3) nine volt battery connected to the needle via an electronic switch (flip-flop to the initiated). The user touches a metal plate connected to the battery's other pole to complete the circuit. Adequate zapping with these needle-based home kits takes at least five minutes per hair, per session and may leave visible, permanent scarring taking the form of either a crater, or a distinct lack of pigmentation over an area of three millimetres diameter or more. 

Assuming you manage to insert the needle properly, the zapping hurts (and does not feel like diathermy) and the automatic reaction is for the hand holding the needle to jump, somtimes pulling the needle out of the follicle. The signal out of these kits is crude and can hurt more than, and differently from, professional electrolysis. And five minutes of pain is vastly different from the brief burst of discomfort from professional electrolysis, per hair. [Note for the initiated: the signal from these home kits is usually modulated DC, but the modulation is of audio, not radio frequency.] 

This five minutes treatment each hair needs does not begin until the needle is correctly inserted into the follicle. Read on ... 

For any kind of electrolysis to work, the needle must go into each follicle at the correct angle. Each follicle's angle (in all directions) is different from those of its neighbours; it may even be growing in the opposite direction to its neighbours. Trying to insert the needle into the follicles of one's own face, while using a mirror, is extremely difficult. To merely see all the follicles oneself is impossible, even with a mirror (or two mirrors, or a hall of mirrors). The user ends up with sore skin, possibly scars for life, and plenty of tears of frustration. 

All this is one-handed; the other hand is touching the metal plate. While attempting to treat the throat area, the user has to pull the skin into a position allowing it to be seen properly ... and hold it there while the other hand attempts to insert the needle ... and keep it still during several minutes of painful, old fashioned, direct current electrolysis. For bad measure, the areas of the throat which are most visible to other people (and thus most in need of zapping) tend to be the areas least easily visible to oneself. 

Magnifying mirrors have a drawback in this application: they magnify the movement of the needle, making orientation even more difficult.

For another opinion of home electrolysis kits click here (external link). 

The same needle orientation difficulties still occur when trying to use a professional electrolysis system to treat one's own face / throat. Until you try it, it is difficult to imagine how hard it is to accurately steer a fine wire into a follicle on your own face or throat. 

Because all these problems affect every hair, every time, multiply the frustrations by several thousands. The money which would be wasted on these kits is best put towards the cost of professional electrolysis performed by a qualified practitioner. Home electrolysis kits using needles are intended for treatment of fine hairs in places readily visible to the user and in those circumstances can work, but still carry risks of permanent scarring and are not recommended by any reputable electrolysis authorities.