It's an interesting question. Crabtree make two ranges, one saying Shavers Only, one not.
Both state they comply with BS EN 61558-2-5, so obviously both have an isolating transformer in them.
Regarding the first range, Crabtree have previously said:
"Hello. We would not advise the use of electronic toothbrushes in our shaver supply units for the sole reason of the British Standard that we have tested them to (BS EN 61558-2-5). The standard does not require the testing of other electronic devices so we cannot assure any compatibility with our product unless specifically rated for the input/output of 115/230V. Thank you for your interest in our Crabtree brand".
The range that
doesn't say "shavers only" clearly states it has a transformer rated at 20VA on the datasheet and this seems to be the key difference.
There's also an MK unit that actually shows a toothbrush on the faceplate and this also states it has a 20VA rated transformer.
Spot the price difference!
https://www.NoLinkingToThis/p/mk-al...ts/222ff#product_additional_details_container
So it probably simply comes down to cheaper transformers with thinner windings in the other products, that would get rather hot / overheat if loads are connected for sustained periods.
This could all do with being made a little bit clearer for the average punter though, as not many will take any notice of "shavers only" - it's the right size and shape so it will work, right?!