https://www.parool.nl/english/takeaways-aren-t-a-new-thing-t...: “takeaways and deliveries are nothing new: they were the staple diet of most people in ancient Rome.”
https://www.businessinsider.nl/fast-food-ancient-rome-histor...:
“Ancient Roman fast food joints were called “thermopolia.”
These restaurants had a bad reputation, but they provided fast and cheap meals to the poor of ancient Rome.”
The poor in Rome lived in multi-story wooden buildings where open fire cooking is not a good idea.
That second link says Pompeii had 150 thermopolia, so I guess not having a real kitchen was fairly common for the poor there, too.
The wealthy would have kitchen facilities in their villa, and usually the middle class in their domus, and would probably usually eat at home (as might their servants and some clients) but even then they might have lunch on the street while in town transacting business.
So I would imagine many of the residents had disposable income for dining out.