The real value proposition of a bodega/corner store is that it it's on your corner, or the one 1/2 a block away. They used to have longer hours too, less so now that grocery stores open late or 24hr. So it isn't the place you went for a big grocery shop, but the place you dropped by when you forgot something or ran out of milk.

They've always been more expensive than grocery stores, doesn't matter if they are local independents or big chains.

Typically the bodega is within a couple minute walk, while the large name brand stores in my area are more like a ten minute drive