After decades in the restaurant business they have a pretty good feel for things. I've heard it said that their employees have lives and families and they show respect for that. My guess is there isn't enough trade to stay open later on Sunday
It's mainly a lunch and takeout place. And very much a take it or leave it place. Food is excellent.
Sundays are generally slow after 6 I would say that's why they close at 7pm.
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