Welfare system that favours single parent families

Contrast the following two scenarios.

1. Single parent with 2 children under the age of 11, works 16 hours a week on the minimum wage, receives 487 pounds (with the aid of tax credits).
2. 2 parent family with 2 children under the age of 11, must work in total 116 hours a week on the minimum wage to receive the same amount of pay.

This clearly shows that remaining single is better than getting married if you are trying to make ends meet.

It would be interesting to know if there are any other equally ludicrous welfare systems around the world?