This is probably not far off from how things already work in distribution. Most restaurants are ordering from the same food wholesalers in a given region. When I go to more "independent" grocers or local chains they still have much of the same offerings as major grocers in my area, so I'm guessing they also order from the same sets of distributors (or lease shelf space to the same groups). And I'm not talking just the packaged stuff. But when certain varietals come in e.g. Cosmic Crisp apples, its like all the grocery stores in the area are getting the Cosmic Crisp apples over the next few weeks with the same sticker and all.

I know for stuff like seafood there is a saturday night 1am fish market near our harbor where significant volume is sold wholesale to restaurants and grocers (but also individuals interested in filling a chest freezer).

So I think already there are just few places to order food wholesale in a given region so those prices are probably somewhat even. Then of course you go to vons, kroger, ralphs, save4less, the local korean grocer, and see different prices for the exact same commodified product like Cosmic crisp apple or 6 pack of coca cola, there is your markup that comes from the grocer itself on top of the regional wholesale price. Grocers like to have flexibility in markup to play psychological games like rotating sales, coupons, and offer rewards programs. Seems that sort of finagling isn't tolerated at the next level of abstraction in business to business sales.

Cost disruptions might be good to put the blame on who exactly in the chain is gouging prices. At the end of the day, the eggs in the egg shortage were not more costly to produce than beforehand. And the egg farms that were culled of their hens, were probably not that much of an anchor on operations given that they probably were not consuming their usual power, water, farmhands probably all laid off, land bought and paid for probably decades ago by this point, way out in marginal farmland where property taxes are probably quite low. Certainly not enough to quadruple the price of eggs. And how interesting how Trader Joes still sold $2.99 dozen racks during this whole crisis.