There's hardly a place in the world (yes, even in Scandinavia) where starting a business entitles you for welfare or the usual labour rights. A typical small entrepreneur has to live with that for years, until the cashflow becomes viable enough to support them employing themselves.
I realize that's not what most people have in mind when they ask for profit sharing. They want to be a part of an already successful operation, and take no risks. And that's precisely what I've been talking about. The process of building a successful business is given little thought, as if they grow on the trees or are being brought to Earth by meteors.
Then there's that thing with businesses statistically being just slightly more often in black than in red. Would your profit sharing scheme involve absorbing the losses as well? How many takers you think it will have? If not them, who will get to absorb the losses, potentially reinvest to weather through rough times etc? The expense would be not negligible, on the order with the profits.