The differences in perspectives between Rehana and Muhammad Ali reflect the difference between an "Eastern" and "Western" view of the world.
"Good Advice is Rarer Than Rubies" is one of several short stories in Rushdie's collection entitled East, West. Rushdie explores the definitive cultural differences between both polarities. In "Good Advice is Rarer Than Rubies," Muhammad Ali's perspective is a Western one. He operates from the belief that the West is the place to go and the East is the place to leave. He displays this when he takes note of the "Tuesday Women" who seek to go abroad with their husbands. He recognizes that people view the British consulate as a portal through which their happiness lies. His advice to Miss Rehana is predicated on the idea that he can help her leave to the West. Given how he personally benefits from this belief, it helps to form his perspective.
The individualism with which he acts reflects his Western frame of reference. Muhammad Ali is a conman who preys on these "Tuesday Women" with his promises of authentic documents. His desire for material wealth compels him to act in an individualistic manner. This reflects a very "Western" perspective where people are viewed as means to an end as opposed to an intrinsic end in their own right.
Miss Rehana's perspective is different. Not leaving the East is what forms her perspective. She is decidedly different than Muhammad Ali because she does not view the West as the best, at all. For her, the West represents a loveless marriage that was "fixed" and something she desperately seeks to avoid. She wants to stay in India. The "good advice" that Muhammad Ali gave helped her to answer the questions that would ensure she would never leave. This perspective is different than Muhammad Ali's because it views the East as fundamentally more desirable than the West.
The more encompassing nature of Miss Rehana's perspective is another difference from Muhammad Ali's. She wants to stay back to serve as an ayah to the three boys in Lahore. She does not want to stay for her own self- interested ends. Her desire to help others motivates her actions. Unlike Muhammad Ali who is driven by money in his actions, Miss Rehana's perspective is different because her actions are designed to assist other people. The communal nature of her actions is more Eastern than the individualistic, Western motivations within Muhammad Ali's perspective.