My friend has a proper pro machine that came with both tweezers/gel and needle probes.
She's not trained to use the probes so wouldn't dream of doing so, but she did do a proper training course with the tweezers. Obviously tweezers won't be as effective as probes but the question is how effective are they - is it worthwhile doing?

It will only be as effective as normal tweezing - you can't kill the hair by doing anything to it on the surface, you need to use a probe to get the current to the follicle.

even if the tweezers are electrical tweezers, the electricity does not travel through the hair shaft to the root of the hair.
Electrical tweezers are a scam.

Thanks, that was my understanding. 
.....so now all I have to do is work out how to get my friend to drop the subject then,