Why does slavery still exist in the 21st century?

http://english.aljazeera.net/programmes/slaverya21stcenturyevil/

Bonded Slavery

http://english.aljazeera.net/programmes/slaverya21stcenturyevil/2011/10/20111010144417942321.html

Immigration / Alabama

http://www.cnn.com/2011/10/24/opinion/singer-immigration-nationwide/index.html?hpt=hp_t2

Revolutionary Daughters - Activate - Al Jazeera English

Revolutionary Daughters - Activate - Al Jazeera English

Brothel in Mexico

http://www.cnn.com/2011/10/19/world/americas/mexico-prostitution-arrest/index.html?hpt=hp_t2

Revolutionary Daughters - Activate - Al Jazeera English

Revolutionary Daughters - Activate - Al Jazeera English

http://www.cnn.com/2011/10/14/us/alabama-immigration/index.html?hpt=hp_c1