There are several reasons, first, although polio is highly contagious, only a very small number of infected people develop severe symptoms of paralysis, and an even smaller percentage died. The majority of people infected with polio have mild gastric symptoms or no symptoms at all, only about 5% have paralysis and only 5-10% of those who have paralysis will die, and this number decreases with access to respirators which were widely available by the 1930s. Polio also generally existed in discrete, local epidemics, rather than global pandemics, so the response was different. Things like the 1918 flu had much higher death rates, and came on very very fast and unexpectedly and so caused fast and strong responses by governments. By the 1940s polio cases or even epidemics were expected each summer, so a long term, lower level response proved more useful than a widespread quarantine.

Poliovirus spreads via the fecal-oral route, meaning you have to get microscopic amounts of poliovirus from an infected person's feces into your mouth in order to get infected, this is the same way norovirus (stomach flu) spreads. So unlike a droplet spread or airborne virus, epidemics did not tend to go global, rather they tended to stay in one area that shared a water supply and where people were in close contact. Imagine the difference between a town experiencing norovirus and one experiencing influenza. Norovirus spreads best in a place like a school, and the people who are not in contact with that school will be largely unaffected, this is why adults without children are less likely to get norovirus than parents and school aged children. Influenza on the other hand is spread by respiratory droplets, so it is present in the environment in a much more widespread way. A fecal-oral route disease does not spread between areas as easily as a virus spread by respiratory droplets, and so doesn't require the same kind of worldwide response, rather response tends to be localized. Widespread or worldwide quarantine wasn't needed because though polio was endemic, meaning it occurred worldwide at a low level, and epidemic, meaning there were isolated large-scale outbreaks, it was not pandemic.

During polio epidemics there were forms of what we would now call social distancing, and everyone who was known to be sick or exposed were quarantined either in their home or in a hospital under threat of legal recourse. During the 1916 NYC polio epidemic anyone who was sick wasn't able to be isolated in a place with their own bedroom and indoor bathroom (which was almost no one in 1916 New York) were legally required to be hospitalized. Swimming pools, movie theatres, beaches, large gathering places, and sometimes even schools were shut down during major polio outbreaks. People were also encouraged not to share food or drinks, to wash their hands, and to not use water fountains or go swimming. Children, who were the most likely to become infected, were often kept close to home and away from friends if their area had known polio cases. People did practice what we would now call social distancing, and many particularly enforced it on their children. Local govenments responded by closing places like swimming pools and movie theateres, by seeking medical funding and equipment from the National Foundation of Infantile Paralysis, and by created field hospitals and large isolation wards should the need arise.

"Polio: An American Story" David Oshinsky

"Dirt and Disease: Polio before FDR" Naomi Rogers