As a kid, I remember seeing the ISI mark advertisement promoting the new standards. Government was very much active in propagating it, and soon even manufacturers started adding it to their adverts. It soon became the standard it intended out to be, thanks to the push from the Government to make it mandatory for everyone to comply with it.
In last two years I had purchased a few electrical goods that didn’t do great, but had the ISI mark on it intact. But I do know for sure that it’s quality was compromised by the components used to make them. This led me to believe that I should never buy goods that are marked with ISI without ignoring any other standards.