system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: Why do most restaurants sell Pepsi instead of Coke, and yet Coke is seen to be a bigger competitor?
gpt
Coke sells way more soda by volume than Pepsi. As a response, Pepsi offers its products to restaurants at a reduced cost, which is why many restaurants carry it. But only up to midscale places -- no nice restaurant serves Pepsi, because Coke has more cachėt, and also you need it for mixed drinks. 

Note also that McDonald's, the single biggest restaurant chain in the world, serves Coke.