I have no clue what state you could be from where soda fountains in the dining room aren’t free refills.

I’m from VA and lived in a few different states. I’ve work in fast food. The syrup and carbonated water combo is cheap. The cup is more expensive. Most restaurants would pay the few cents and keep the customer coming back. I always used to refill my soda when I left places. I’ve been cutting back on soda, so I don’t do that anymore.

The ‘trick’ the fast food workers are supposed to look out for is the customer asking for a cup for water and then filling it with soda. Most cashiers don’t care enough to track you though.