In theory. In practice things will evolve in subtle ways that will effectively insulate managers - scheduling meetings at unconvenient times, passing rules that allow for fewer and fewer people to make big decisions, etc.

I mean, even regular businesses in practice end up this way - nominally with lots of shareholders, practically run by (and for) a few powerful individuals. That's why we have a concept of "activist shareholder" - in theory all of them should be "active" but in practice almost no one is, so the few who do are labelled (and often "bought" one way or another).

And I'd guess that a restaurant doesn't have the scale to shoulder a management tier and the costs involved.

Sure but nobody is pretending that there shouldn't be some kind of way of making decisions in these organizations. The point is that the people making those decisions were chosen by and accountable to the workers at the firm, not external shareholders. The incentives are completely different.