"tlbs101"
About 30 years ago, I took apart a 9V "battery eliminator". It had the physical form of a standard 9V battery, but with an AC cord extending opposite the 9V battery terminals. I took it apart because I could not believe they could make a transformer so small, so imagine my shock when I found none. Instead of a transformer, there was a series electrolytic capacitor and a 2 Watt resistor (that got very hot when the device was operated). In addition there were a few diodes including a power zener and some filter capacitors. That was it -- no isolation and a series capacitor. This device was legally marketed.
** I dispute that last claim.
You must be talking abut the US back in the early 60s, where for example one could sell tube guitar practice amps to budding musicians which effectively had a live chassis.
Manufacturers back then took sole responsibility for the safety of electrical devices they sold and there was no requirement for agency approval or compliance with government regulations.
In most developed countries, one of the very first electronic devices to come under compulsory safety approval regulation were " battery eliminators " - cos so many of them were soooooo damn dangerous.
Your example is a classic and thankfully a relic.
..... Phil