As for why she needed to build machines, it was entirely to enable more efficient mass production and improve the quality of Iodized Salt. She couldn't possibly rely on workers for every single step; they might not do it properly.
The salt-making machines Claire researched were only semi-automated. Many steps still required workers. It wasn't that she didn't want full automation, but neither she alone nor the technology of this other world could achieve it. The technology tree here had been invested almost entirely in magic, with barely any industrialization. Claire was practically starting from scratch.
Besides, hiring workers would create jobs and directly raise Nafu City's income levels. Since Claire returned, the basic wages in Nafu City had already increased by nearly fifty percent. Once the Salt Factory was completed, they were expected to double outright.
The job opportunities created by an industrial pillar weren't limited to factory workers. For example, carpenters were needed to make the wooden boxes used to hold Iodized Salt, and the carpenters needed lumber, which meant people were needed to fell trees. Then there were the raw materials needed for Iodized Salt—seawater, laver, kelp, and so on—all of which needed to be collected.
As long as the Salt Factory created demand in those areas, corresponding upstream job opportunities would emerge, directly or indirectly creating hundreds of jobs. If this continued, Nafu City's economy could develop rapidly.
This showed just how significant an industrial pillar was to a city's development.
If there hadn't been so many benefits, Claire wouldn't have been in such a hurry to open a factory and sell Iodized Salt.
But what Claire needed to solve now was still the salt-making machinery. Extracting salt from seawater wasn't as simple as she had imagined. It wasn't enough to merely boil the seawater dry.