Brian Gaff wrote

Don't know about that, I've always thought that inductive chargers are
pretty inefficient, even if driven at high frequencies.

Doesn’t matter when charging a phone or a tablet.

I suppose you could have a bit battery and a cable to your device which
would be safer than a mains connection of any kind.

Perfectly possible to design the charger properly so that
it is always completely safe even when something has failed.

polygonum wrote
wrote
There is a very thin barrier between mains and usb output. If it
breaks down you're fried. A great number of noncompliant chargers
exist that have very inadequate insulation. I would not do it.

I assure you it is not my intention to do it! I expect many people do,
though, and it made me wonder. If I did want to, I'd probably think to
use my battery pack USB charger or, preferably, charge before bath, but I
don't want to drown my phone or tablets.

I was also imagining the next generation of shavers and toothbrushes
possibly having USB charging as standard? Or, wireless charging but with
the charging plate being fed by USB.