The difference in Karachi and Dhaka urbanization is leaving room for offsets, e.g. at least fifty or so feet of space from the sidewalk. So you have room for some air and light to infiltrate the windows.
Dhaka govt. city planner ullus will take bribes and allow people to build a ten story condo complex less that ten feet from the sidewalk. Right next to the boundary wall of an airport. Just horrible. Dhaka looks worse than Kowloon now. But yes there are trees. And Paan/Chai/cigarette stalls every few feet, even in wealthy areas. No regulation, no oversight.
The look of congestion in Dhaka comes from these unfortunate events and will affect the livability index.
Once a building goes up, it will be fifty year before its brought down, unless an earthquake happens or a sinkhole develops first.