There's a short video on youtube where Patagonia discuss ethics and bringing manufacturing transparency to customers, and they go on to discuss problems in their own supply chain and what they're trying to do about it. It's quite refreshing, though mind you the transparency approach is like a branding position in itself, but still commendable.
Someone with more knowledge may want to talk about H&M's 'ethical line' which at least on first impression makes you raise your eyebrows a bit, since it's similar to how Shell organises 'green eco events' around the world while simultaneously basing its core business on hemorrhaging the environment. In the case of H&M their core business model is centred around fast fashion, the complete opposite of being eco. They're basically PR and branding campaigns I feel, as a good chunk of the customer demographic want to socially identify themselves with progressive/ecological brands to align with their principles, so H&M just goes and creates a new line for it but doesn't interfere much with it's main supply chain (unless it gets caught). Like you mentioned, It's similar to how organic foods have become popular in the recent decade with well-heeled shoppers - little do they know that fundamentally the organic food you find in supermarkets are still messing up the eco-system and not grown sustainably. But organic food is a growing premium market, and so is ethical fashion, so businesses will go for where the money is. Which is better than having nothing though, and it's a start.
There is another brand in the UK selling shoes - TOMS - where for every pair of shoes you buy, they donate a pair to a kid or help a poor community in some way. Really great idea, and again it's a core part of their brand identity.
I attended a blockchain conference a few months ago where people were discussing use of blockchain and digital certificates at each stage of manufacturing to maintain complete and transparent traceable history for each individual product. It's a great idea in theory but the big elephant in the room is that you will have to get a very varied set of companies, suppliers, logistics providers, governments and custom officials (of different countries) to all sign up to a common platform and agree to scrap their existing processes, or run two auditing processes simultaneously, and neither scenario is realistic.