I'm not sure where you're located, but Dig Inn (https://www.diginn.com https://www.diginn.com) started in New York and looks to be spreading in Boston and while

I'm not sure where you're located, but Dig Inn (https://www.diginn.com https://www.diginn.com) started in New York and looks to be spreading in Boston and while not necessarily a $5 lunch, seems to fulfill most of your criteria. It may not offer as large a selection as traditional canteens, and is very bowl-focused (who isn't in 2019?) but I thought it a pleasant enough experience.