> Every other way of buying groceries if one limits themselves to buying from well established entities that are big enough to support it, which is a much smaller subset of those who could supply food now.

No, its not. Even independent groceries (and independent convenience stores that have grocery items) take EBT. There’s essentially no place you can buy groceries where you can’t use EBT. There may be a minimum viable scale, but its apparently very close to the minimum-viable-retail-operation-with-any-grocery-items scale.

Uber is playing catch-up, not establishing an edge (much less an edge protected by a moat) compared to other ways of getting groceries.