You don’t owe tips to people who hand you food in a bag.
I’m in NC and the Jersey Mike’s here, a sandwich shop, asks if you want to leave a tip on the screen when you pay. I say no. Pretty sure Subway asks, too, but haven’t been to one in a while since trying Jersey Mike’s.
Tipping the counter help would be like tipping a chef at a restaurant. Tips are for waiters and waitresses that serve the food at a table.