It depends on why the machine was invented and where it is being used. Rather than having cement truck mixers, cranes, metal scaffolds, and conveyor belts, it is easier and cheaper in India to hire people for a few cents a day to mix the cement by hand, and carry the cement in baskets to where it is needed on bamboo scalfolding. Why invest large amounts of capital in machines that need to be maintained and replaced?
What you saw in India was not that. What you saw was how a Tradition oriented society and and overly interventionist Government screws up a market. Labor was cheaper in India because the Govt of Indias economic polices made the machine difficult and expensive to import at the same time making internal development of the same machine substandard or nonexistent.
What I saw was a developing country operating on free market principles. Labor intensive activities also work on the political level, i.e., they provide employment for the poor and uneducated. Of course, you can always ship the problem out to a richer country like Mexico does.
US businesses are relocating their operations to China? Why? Cheap and plentiful labor. There is a reason why we don't manufacture TVs anymore in the US. No amount of efficient machines is going to change that fact.
Oh, you're going to have to go some to justify this one!
I would accept "a labor intensive solution is often cheap enough not to warrant coming up with a machine," but not that it is never cheaper. My company makes paper. Among the many things that we do is to make deals with companies that make machines to do things with that paper, like fold them into complex boxes and then sell the package, machine and paper "blanks," to a thrid party. It's often easier for our prospective customers to get someone to put the product into a simple box than to invest in the automated system, even if it is cheaper in the long run.