Urdu speaking are living in a city that enjoys most of pakistan commecrial activiteis because of import and export forrest of the country. There is no rocket science behind why they are less likely to opt for imigration, karachi has more options than any other city of paksitan. Going for eduction and following no tribes is out of same reason they living biggest metro of pakistan.
Urdu speakig are in tough competetion with tribal evils of rural sindh and punjab as they love to support MQM despit knowing they are bhatta khor, target killers, and haramkhor.
Rural sindhis and punjbis are ignorants but it make urdu speaking worse in this term as they are choosing MQM despite being most educated.
intestingly, once I said karachiietes claim to be most educated yet voting for mqm, most karachiietes on this forum denied the claim.