Why are contract employees are discriminated in wages?

While regular governent employees enjoy all benefits like peridodical pay-scale revisions, hike in DA, HRA and CCA, apart from Interim Relief and all kinds of perks, millions of contract employees working in various government departments/organisations in India are denied similar revisions in their consolidated monthly pay which is insignificant compared to the one drawn by government employees? Nobody is raising any voice in support of contract empoyees? Why the governments are not saying a word about them? Are we not human beings? While government employees who ususally work from 10.30 AM/11.30 AM till 5.00 PM are deputed to all kinds of official tours which includes unofficial pleasure trips around the places of official works with all luxurious amenities, the contract employees are denied everything despite toiling in the related official works even beyond ofice hours every day all through the year. When will this discrimination end? Will someone responsible answer?