They have more techniques too, like having store- or region-specific models that probably are all essentially the same but have different model numbers and slightly different feature sets just to make searching for reviews and price comparisons more difficult.

Sometimes they aren't essentially the same, but instead different in invisible ways. DeWalt grinders at Canadian Tire used to use plastic parts where metal was typically used. Outside of the different SKU it was difficult to tell the difference.

Walmart is notorious for this - they push really hard on suppliers to reduce prices, and suppliers usually do so by cutting quality. However everyone still pretends it’s the same (including identical outside appearance).

This so much. At least over here it's completely impossible to find reviews of whiteware (refrigerators, washing machines etc.), at most a handful on the local reseller homepage.

even TVs suffer from this - tons of european models have different numbering/code, and unless you are die hard fan who understands various manufacturers product lines year by year, looking for products in Europe based on ie US reviews can get tricky.

That is more to allow big box stores to advertise "price match" when they know no one else as the "exact same model"

See this Drill is DW345, we sell DW350, it is 5 better

Absolutely, it's everywhere, not just in tools. Brand X known for quality decides to, well like you said, drop production cost and 'harvest the brand value'. Then after a while when the reputation is sullied, the same conglomerate / holding company launches another 'upscale' brand. Rinse and repeat.

I almost feel like it should be deemed fraud or false advertising, although I have no idea how we should draw the line and ultimately we probably shouldn't.

That was liking riding along in your mind as you constructed your thought! :)