I know this is an ancient thread, but as a data-point, in the SouthEast USA, the “ring on the right” was very well established in my child-and-young-adult-hood (80s-00s) as an indicator of widow/er status.
That’s changing, I think in part due to that advertising campaign noted in this NY Times article that started aiming at women with disposable incomes.
If I see a right-hand ring, I start checking other data-points in my head to see what box I slot the person into - if they’re older, or more conservative, or wearing other religious jewelery, then it’s likely they’re a widow/er. If they’re younger, or more “professional,” or they’re dressed in very natty stylish clothes, then it’s more likely to be an “I am woman hear me roar” ring.
Personally, I don’t wear my rings on my hand. I have them on a chain around my neck, as does my husband. We both work places where rings are either an inconvenience or outright dangerous. Despite that, I do think that the switching hands idea is a sentimental and sweet one. As much as I’m all over empowerment, I do feel a little sad that this tradition (as subtle and spotty as it is) is being co-opted by a movement driven by an ad campaign.