They Wasted a Perfectly Good Sandwich/Headscratchers

• I always wondered why the director couldn't at least show that the food was partially eaten at least. It always bugged me that people in movies and TV often order food without eating it... even if they don't get interrupted.
  • The meta reason for this whole trope is that food is anyway a nightmare, continuity-wise, and it's hard enough to keep it straight so that you don't get a whole load of nitpicky emails about how the food shifted from shot-to-shot; it's presumably just a bit easier on the poor continuity director to keep what food there is whole rather than having to juggle which bits look eaten versus which bits don't.
• If they aren't going to eat, then why do they show them ordering in the first place?
  • To add to the ambiance and realism of the scene. While the actors might not be actually going to eat, the characters generally are; generally, in real life people don't just go into restaurants, sit down, have a long conversation and then get up and go without ordering anything -- they go there to eat something, so to eat something they have to order it.