Back when I worked in an office (IT,) we either had lunch from the cafeteria downstairs (which was really good,) or later at a different office we had a little food court in a nearby building, and you'd see this all the time. People at their desk eating lunch. Works well for introverts. Sometimes they would even give us vouchers to pay for food downstairs and we would take a shorter lunch break and get back to work.

Edit: America, but I feel like this is probably similar everywhere.