Buyout Option

From many of the post ive read in citehr regarding the employees willing to leave the organization by using buyout options, its clear that company retains the right to pay salary in lieu of notice period. In that case its a one side and its in the hands of individuals of an organization. If at all company wishes their employees to serve notice period, then why is that such a clause to be added in appointment letter.In present scenario, most of organization would prefer candidates who would join within a month and if the present organization doesn't allow him for the buyout option, probably he'll be at stake of his job.
Isnt there any labour law to subdue such clauses ?

Quite a valid point , but there is no law as such on notice period.
The release is mostly frictional. Transition costs its price.
Lets hope as the market mature and such practices settle for the best !