Simply because most steps in the commercial graphic design process must almost always involve working on the computer, concepts for packaging like Senor John's BBQ Sauces still choose to make good use of one's tools at hand.
The design of the paper shopping bag, the boxes and these glass bottle labels have all been executed with distinctly hand-drawn techniques, inspired by the cardboard signs that the homeless hold up along city streets. This aesthetic choice was a very intentional one, given that the profits made in the sale of these barbecue sauces go to Feeding the Nation's Homeless.
A black marker appears to be the most used medium to create the block letter text and outlines of various illustrations. Lorena Mondragón even included facts about street people on Senor John's BBQ Sauces packaging.