why is it taking more time like 2-3 weeks for some people to receive passport even after VO told approved

[andhrafan]

I heard from a couple of guys in kingston Jamaica that even when the VO told visa approved they are facing problems

 

one guy was asked to come back after 2 days for additional processing

 

other guy also told was approved and later rejected for DUI i had seen some where in this forum

 

other people i heard they did not receive the passports till 2-3 weeks

 

why is this happening, is there any background check being done even after visa officer tells approved