>>510127312they’re usually reacting to a specific image of communism, one that mostly comes from the 20th-century communist states like the Soviet Union, Maoist China, North Korea, or Cuba. They're often thinking of forced equality + dictatorship + poverty like your example of Cuba, where many doctors and janitors live on similar state salaries, and there’s very little opportunity to change that.
One side hears “Gulag” and the other hears “free healthcare.”
In many real communist states, social mobility was limited, wages were flattened, and the system discouraged individual ambition or entrepreneurship. So your image of everyone being “paid the same” and not being able to advance does reflect how it worked in places like Cuba or the USSR.