Why do different countries use different poverty line?

The cost of different products for consuming is not the same in different countries. It varies country to country. In India, the cost of a parker pen is 200rs whereas, in the USA, the same pen costs 22 dollars which are approximately equivalent to 180rs. Due to this, their cost of living and cost of fulfilling their necessities is different. The standard of living in different countries is also different. These are the reasons different countries use different poverty line. There is a term called the world poverty line. People living on less than $1.90 a day are below world poverty line which is defined as extreme poverty.