There is nothing wrong with screwdriver testers, Professionals should have no difficulty learning how to use them, their safety and their limitations but sadly I know many who have failed to understand and disregard them, simply because they are not in the curriculum but give them a bit of high tech kit like a phone or MFT and they soon sort that. Let's be honest here; far too many electricians seem to fail miserably to understand how to fault find if the number of 'repeat visits' I'm asked to sort out is anything to go by.
Absolutely, it's the basic, lack of understanding.
You, and others, might well be aware of the risks and limitations, fair enough, I`m not getting at any of you for that.
What I am against though is people using them (slightly gifted DIYers, the gen public and a few pretend electricians) placing reliance on them and disregarding risks and limitations.
My comment about them being banned and outlawed was indeed rather tongue in cheek but generally they are not a good idea and best not used - that is a generalisation, a quick answer if you prefer, there`s a lot of people who do not have sufficient knowledge I`m afraid, it`s that that is the problem. I avoided lots of caveats, ifs, buts etc by making the statement, most folk are best avoiding these things unless purely to turn a screw lightly (have removed said neon and resistor first).
quite a few folks gets Electric Shocks, thankfully not all of them get Electrocuted, let`s decrease the likely incidents if we can.