I believe the answer is: A.Smith knew that the invisible hand of the market was not concerned with the health of the laborer.
The power of invisible hand in the market only care about the power of supply and demand which would determine who will obtain the most wealth. Even if the process could disregard the wellness of many people, as long as the demand is met, consumers wouldn't put too much thought on the laborers.
We have the choice to go back in person but no we don’t have to take the leap test.