Sharing the lunch bill

I'm not a fan of the "let's just divvy it up" at lunch. Most of the time, everyone's meal is about the same price, so no big deal. But invariably, there is someone who orders the full rack of ribs, or the two glasses of wine, when everybody else is having a sandwich and tea. They're usually the first to say, "let's just split the bill." In today's case, he also wanted to short the tip.