This exists in the UK, it's called Unbound. They've been around for ten years and they've done... fine. Some decent books. But their business model has not exactly conquered the world. As an author myself, I would never consider defecting from my "legacy" publisher to a service like that, because my publisher has been extremely valuable to me.
The percentages aren't particularly relevant to me, because I live off advances, not royalties. Sales are still meaningful, because they help determine what advance I get next time, but in my case the idea that I'm getting a cut of each one is basically just symbolic – I've already been paid. Just one of many reasons I could never have had the same career without my "legacy" publisher.
(I should note that your percentages are way off, by the way – in the US I "get" 25% of the cover price for digital and between 7.5% and 25% for physical depending on the edition.)
