Are you talking about IT & ITES companies in India or some foreign country? In India, there is no such exemption from any labor enactment. Even the provisions of the Industrial Disputes Act are applicable to IT companies. True, there are some exemptions given to them following the IT Policies, but that will not replace the labor acts. The provisions relating to the engagement of women during the night are not available exclusively for IT companies but are available to other sectors as well.
The fact that IT companies have their headquarters in foreign countries is not a genuine reason to get exemptions from labor laws. If foreigners want to set up in India, they should follow the rules of India. Permission to set up a unit in India does not mean that they can run it without registration, without following the health, safety, and welfare provisions applicable to other companies in India. IT companies are required to get registration under the state Shops and Commercial Establishments Act, submit annual returns, follow the rules relating to the payment of wages, enforce all social security schemes in India, and so on. Merely being in the Soft Technology Park of India does not mean that they can run the establishment as they like. As already mentioned, in case of disputes, the Officer concerned of the Labor Department can intervene and mediate. What's more, they can also form a Trade Union.