Why is cheap labour inethical?

Do you mean unethical?

I can't answer your question specifically but bear in mind, Nestle is probably the worst company you will every come across.
I mean some of the atrocities committed by them make some dictatorships look good.

I think labour below the living wage is unethical, cheap labour isn't necessarily.
Essentially, it's exploiting people who need an income, and will do any kind of work for any hours so they can just manage to support themselves, whilst the company makes greater profit margins. Nestle could afford higher wages in India, or possibly even minimum wage in a developed country, but instead they are cutting costs.
However, they are providing paid work, so it could be argued the workers are better off being exploited in this way than they would be if the factory didn't exist. Of course, then there's the fact that they can afford to pay higher wages - which is where you could look at the living wage and see how good/bad a deal 25p per hour actually is.

I think labour below the living wage is unethical, cheap labour isn't necessarily.
Essentially, it's exploiting people who need an income, and will do any kind of work for any hours so they can just manage to support themselves, whilst the company makes greater profit margins. Nestle could afford higher wages in India, or possibly even minimum wage in a developed country, but instead they are cutting costs.
However, they are providing paid work, so it could be argued the workers are better off being exploited in this way than they would be if the factory didn't exist. Of course, then there's the fact that they can afford to pay higher wages - which is where you could look at the living wage and see how good/bad a deal 25p per hour actually is.

Thank you, this is exactly the help I needed!