considering the miasma theory was the dominant theory regarding the cholera transmission, what is the significance of both sets of houses snow studied being in the exact same condition of poverty

Not everyone in the Soho neighborhood of London got sick, just those who drank water from the Broad Street pump. Thus, the cause seems not to be the air as in miasma theory, but something else.  

Explanation:

There were 2 competing theories on the origins of cholera before the bacterium was discovered in 1883. One was miasma which held that cholera was caused by decaying matter in the air.  John Snow on the other hand put forward the idea that it was actually caused by a germ in the drinking water. John Snow carried out studied in the Soho district of London during a virulent cholera outbreak and his theory was that the water from the Broad St. pump was causing the infections. It is significant that some houses had cholera and others didn't even if they were in close proximity because miasma theory said the contagion was in the air. By also considering why some people in the neighborhood were not getting sick he was able to get evidence that it was not the air that was causing the outbreak.

protectionism fosters competition and keeps price regulated is not an argument in favor of protectionism.