In Berlin at least there is a strong correlation between income and access to a car. Poor people take public transit and bike much more. They also tend to live close to major roads and suffer from noise and air pollution much more.

75% of the people with an income below 1500€/month don't have a car in Berlin. Only once you reach 3000€/month income (that's roughly the median income) the majority has access to a car.

Poor people can't afford cars. Cramming whole families into cheap apartments of questionable legality is not a great way to live, but you do what you have to.