Industries were and are free to make investments in whichever state that provides them a favorable investment climate.
At the same time, it would be natural justice for giving preference in unskilled labor jobs to local populace as the industry is being set up in their land and neighbourhood.
Migrants from other states pour in huge numbers and are prepared to work for lower wages at the cost of the local people.
If industries cared only for lowering wage costs for unskilled labor jobs, then they should have set up the industry in the states from which these migrants are coming from in the first place!