Families in Australia, NZ, U.S. etc have a good work life balance. Eg my former neighbour who migrated to NZ, when she had her kids, was home by 4pm. In the meantime she leaves the kid at child care. My good buddy's brother in law is back home by 5pm on weekdays while the wife is a stay at home mother. My cousin who lived in Zurich was working from home 3 days a week when she had her baby. Now she has moved back here with the family she is forced to hire a maid because both husband and wife are working. The UK has just introduced share parental leave for newborn babies, parents can take up to 50 weeks of leave, shared between them. Of this, 37 weeks are paid leave. That's 9 months of paid leave.
Unlike in the past, parents are working longer hours these days and many bosses are not as accommodating to working mothers as in the west.
Hope that answers why some families need a maid.