Disclaimer: I worked at fast-food as a kid, used to live on multi hectokilo USD after university and live on just under 1 decikilo USD now. People making less

Disclaimer: I worked at fast-food as a kid, used to live on multi hectokilo USD after university and live on just under 1 decikilo USD now. People making less have a hard time affording a baseline of basics. So marginal propensity to consume (MPC) is higher for those inelastic demand costs. It's also harder to get a bank account, keep good credit, get discounts like coupons or shop at big-box stores (eg some areas only have convenience stores) and there's less social pressure to save and shop wisely. Also, when you have only $20 and have to choose between food and gas, it seems impossible to look at a smartphone app like GasBuddy when data is prohibitively expensive.