The idea behind penalizing the Principal Employer is the end result. After all, the workers working through contractors are working in connection with or incidentally to the principal employer and on the premises of the Principal Employer, for the benefit of the principal only.
Who is getting the end result, i.e., the principal employer? Everyone knows the contractor is only an intermediary for administration purposes.
Contractual/Casual/Outsourced, etc., are only classifications of workers/employees recognized under law, but ultimately, work is being done for the principal employer.
I would like to draw attention to the definition of "Employee" in the PF Act. An "employee" means any person who is employed for wages in any kind of work, manual or otherwise, in or in connection with the work of an establishment, and who gets his wages directly or indirectly from the employer, and includes any person:
(i) Employed by or through a contractor in or in connection with the work of the establishment.
In the ESI Act, an "employee" means any person employed for wages in or in connection with the work of a factory or establishment to which this Act applies and:
(i) Who is directly employed by the principal employer, on any work of, or incidental or preliminary to or connected with the work of, the factory or establishment, whether such work is done by the employee in the factory or establishment or elsewhere; or
(ii) Who is employed by or through an immediate employer, on the premises of the factory or establishment or under the supervision of the principal employer or his agent on work which is ordinarily part of the work of the factory or establishment or which is preliminary to the work carried on in or incidental to the purpose of the factory or establishment.
The above definitions clearly state that any person who is working either through the contractor or directly in connection with the work of an establishment/factory shall be considered an employee for the purpose of both legislations.
For contribution/compliance, the provision has to be done by the Principal Employer or ensure that the compliance is being done.
These legislations being social security, the liability is fastened on the Principal Employer to provide all benefits envisaged under the Acts because the Principal Employer is the real beneficiary of the work done by the employees of contractors also.