You posed some very good questions, Fieldthistle, not stupid at all.
Some places in my area have special menu items that are billed as "15 minutes or less" that are great for carry out.
At one restaurant where I was the chef some items just didn’t travel well and were not available for take out. We did a decent carry out business, although some of the line cooks would whine about it. If we got a large carry out order in the middle of the lunch rush, it could get scary for the kitchen. Take out orders were only about 10% of our business on average. If we did 150 covers at lunch, we very seldom had more than 15 carry out orders. I wouldn’t have minded doing more.
The main reason we didn’t discount take out orders was to pay for the high quality containers we used. We didn’t upcharge for carry out, but the containers we used cost more than styrofoam and cheap hinged plastic. Hope I answered some of your questions.