By popular request... An internal examination of the slightly tacky looking inline 6VA power supply I bought at the same time (and from the same supplier) as the 12W and 18W units.
The case is distinctly tacky, being a clip together box with wires coming out both ends. Mains in, and 12V out. No cable grip or terminal shielding. This is the sort of thing all-trade installers would poke through a hole in the ceiling for a 12V downlight with a couple of bits of terminal strip floating above the ceiling.
It's reasonably well built inside but saves space by ditching filtering, and even a full wave rectifier. There's just a single diode rectifying the mains.
Other than that it does use a decent driver chip with optical feedback from an adjustable threshold detector for accurate voltage control. The secondary windings have the appearance of being better insulated than most, and are brought right out of the transformer and directly to the output circuitry. There is an obvious separation between the mains and low voltage sides with an anti tracking slot at the closest part to improve separation.
The person who designed this unit has obviously been working to a size/cost restriction, but has made something that is actually relatively safe looking.