Question

Why do different countries use different poverty line?

Answer 1

Poverty line is the most suitable measure of poverty. It measures poverty on the basis of income or consumption levels of people living in a particular region. 
The per capita income in different countries is also different, per capita income is higher in developed countries as compared to developing countries. 
Poverty line varies with time and place, owing to the different requirements of the people living at different places and in different countries.
People have different needs and different choices depending where do they lie in the poverty line.

Answer 2

Different countries have different poverty lines because the cost of living varies form country to country.In some countries the income required to live a decent life(above poverty line)is lower than the income required to live a decent life in another country.The price of commodities and the cost incurred for accessing heath and education facilities are different in different