In many ways cars are also more useful to people who are poor. You're more likely to work in some out of the way place without good transport links rather than

In many ways cars are also more useful to people who are poor. You're more likely to work in some out of the way place without good transport links rather than an office in the big city and taking taxis can get expensive. If you look at jobs in construction "must have own transport to get to the job site" is often listed as a requirement, less so for programming jobs. Poorer people are more likely to holiday by packing their family into the car and driving somewhere rather than getting an international flight. They can also be used to transport stuff around when moving etc. In short cars provide a great deal of flexibility and utility for the cost.