In a lot of countries, ID is not mandatory, and government-endorsed photo IDs are expensive and time-consuming to acquire. As such, people with a high income will be more likely to have them.
That applies doubly so for a passport or driving license -- people with more money are more likely to have a car or travel overseas, so more likely to have those types of ID.
That applies doubly so for a passport or driving license -- people with more money are more likely to have a car or travel overseas, so more likely to have those types of ID.