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.<p>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.<p>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.
The demand for this service isn't modern. (That's just a hook by the journalists.) A key advantage of a waiter/bartender jobs has always been the immediacy of tips: you have cash in your pocket the very first night.