It's entirely power imbalance, and that can be addressed by policy. Fundamentally, Capital needs Labor as much as Labor needs Capital. There's no economic reason a capitalist contributing nothing should not expect to starve, but a laborer who contributes nothing should expect to, it's just the current market climate and political policy that these are the case such that the imbalance of power perpetuates itself.

It seems you could have the opposite case from today, with Labor concentrated into large unions which lobby for and win things like overly (but not disastrously) high Basic Income or slightly too relaxed intellectual property law, strong-arming a capital class made of small mom-and-pop firms and individual retiree-investors, avoiding providing the returns that would be seen in a more efficient and balanced market.