A working bicycle can be found for under $50 in even the most expensive cities, have $0 in operating costs, and will last for decades. There are likely no other personal transportation options which offer that.
Get out of our bubble. Some people have $0 and literally can't afford anything in their budget or to plan more than a few weeks ahead... They can't account for unknown events, and frankly don't need to worry about going bankrupt because of an accident.
Poverty is fucked up.