Victoria is a game, but it is based on a pretty solid model of economics and society.
Just because you would like if people move to another place , because it seems macroeconomically more profitable, doesn't mean that indivdual people concerned with their individual needs agree with your global point of view.
Imagine a province with mining RGOs and compare it to a province with grain farms. Which is the more pleasant country (and which one is likely to be more inhabited)? The fertile agricultural region or the barren rocky land with almost no farms, but lots of mines ?
Sulphur is traded for expensive prices and hence people can (with the help of labour shortage and trade unions) earn more. But that doesnt mean that it is very healthy or pleasant to work and live in such a environment.
This is even true in our age, but in the Victorian age people didn't even need much extra money for goods like entertainment, cars etc. People were more or less happy staying in their villages and they only moved when the villages became overcrowded (and hence people became "unemployed") due to increased population growth from better medical care and sustainable food surpluses.
Please understand that people would see the additional earnings in inhospitable regions just as a compensation for the inconvenience. Hence they will not move for money only, but only in combinations with other reasons, like unemployment and/or religious issues, unhappiness with the government etc. which are simulated in the militancy factor.
Btw. the human history knows only very few cases of government initiatives that forcefully moved people out of a region to another region (e.g.Stalin and the Chechens). Normally the only way the government had to encourage migration were either incentives (e.g.like the Soviet Union was paying premiums to all people working in North Siberia), penal colonies (which are unfortunately left out of Victoria) or changing the social structure, e.g. land reforms or education, which are simulated by the split function and the conversion function in Victoria. So if you "educate" people in agricultural states to learn the trade of craftsmen they will move sooner or later into the states with factories - sounds pretty realistic !
