This is a great question to think about! I must admit, I can't find any direct examples of how the conflict between man and technology is depicted in this story. However, I can find an indirect one, which relates to the way in which the realities of WWI increasingly impinge upon the lives of the boys and their family. Consider the following quote and the way that it mentions various war scenes and how even those around them are being impacted by the events of Europe:
And during that summer, strange names were heard through the house: Chateau-Thierry, Amiens, Soissons, and in her blessing at the supper table Mama once said, "And bless the Pearsons, whose boy Joe was lost in Belleau Wood."
One of the things that WWI is infamous for is the way that more soldiers were killed than ever before thanks to the rise of technologically sophisticated ways of killing, such as the machine gun and advanced weapony, bombs and artillery. One of the factors of "The Scarlet Ibis" is the way that behind the conflict between the narrator and his brother, Doodle, there lurks a much bigger conflict: WWI. These references to WWI could be said to be an indirect example of the conflict of man vs. technology.