Spain wished to compete with Portugal for trade.
The two types of farm owning developed slavery because the owners of them were allowed to have slaves. The encomienda system was based on the idea that conquerors should have slaves to work for them, and it similarly applied to sugar colonies that had slaves on them. They were responsible for a lot of trafficking of slaves from Africa.
First of all, the passage mentions street children by saying "children pitching pennies" and "kicks and cuffs are their daily diet". Also, pollution is touched in this passage as it mentions "summer stenches" which are bad smells that come because of urbanization and the drains that have foul smells (hence they mention "sink"). We also see how neighborhood noises and noisy people from all around the area show up in urbanized areas because of cramped spaces. Hence, quarreling is mentioned here as well as instances of profanity.
