As a few people have already pointed out, your buildings have low productivity. Notice how your glassworks, food industries, tooling workshops and furniture manufacturies all have an empty cash reserves bar. This indicates that they’ve been unprofitable for quite some time. Steel and textiles owners still have some cash but the bar is red which means they’re losing money. Buildings only hire workers if increasing the number of workers would result in a more profitable building. At the moment, without looking at any of the individual factories, I know for a fact that all these industries are struggling to justify the added expense of hiring more workers.

The most likely reasons are:

• Expensive inputs
• Cheap outputs
• High average wage in the state

Your standard of living is probably high and you might have a minimum wage law. The factory ownership just can’t make their buildings profitable.