December is also called Christmas season because we decorate shops and home to remember that we have to buy gift and food to prepare Christmas and New Year celebration. That period is generaly busy not only for seller who have to send lot of parcels, not only for internet ecommerce but also for every once. That period show us that we MUST spend our money. That period is typicaly for consomer society.
If you don’t have money what do you do. You just feel the pression that you are out. That is why I don’t like Christmas season