This is not a question of scale — even if the “chemist’s flask” were the entire Earth.
They stop reactions at optimal times, and scan through products of their reactions with high-tech equipment to find trace amounts of the product they seek.
In the time of the early Earth, Airgas, the supplier from which the researchers obtained their materials, was not around.
According to a bedtime story popular with materialists, unguided forces alone can explain the coming into existence of the very first cell.
COVID-19 isn’t our only pandemic. There is also a pandemic of loneliness and despair.