during Shabbat a Jew also faces restrictions on what they may may do outside the home, such as carry objects; this presents difficulties for ex, new parents, as much of modern life takes place in the public sphere. carrying objects is allowed within the "private domain", however
a simple way of resolving this issue is by redefining what the "private domain" entails; the eruv is one such method. by paying the city to allow the communities to erect these domain markers, they can fit the rigors of the Orthodoxy into modern life, w/o taking on undue burdens