How was the life of an enslaved person living in the city much better than a slave on the plantation

They were simply not needed as much.

Explanation:

Those who found themselves in the countryside didn't have as many machines compared to those in the city.

In the early 19th century, most enslaved people in the US South performed primarily agricultural work. By 1850, only 400,000 enslaved people lived in urban areas—where many engaged in skilled labor such as carpentry, blacksmithing, and pottery. Almost three million worked on farms and plantations. Because most of the agricultural output of the South was produced on large plantations, more than half of all enslaved men and women lived on plantations that had more than 20 enslaved laborers; about a quarter lived on plantations that had more than 50. Large plantations had field hands and house servants. House servants performed tasks such as cooking, cleaning, and driving, while the field hands labored for up to 20 hours a day clearing land, planting seed, and harvesting crops. Although enslaved men and women sometimes were able to exercise a degree of autonomy in their work—such as on rice plantations in South Carolina—field hands typically worked in a gang-labor system, under which large groups of enslaved laborers toiled under the supervision of an overseer.

my best guess would be: d allusion

makes the most sense