In early years(1850 to 1890) tram lines are slower and more expensive then busses (stage coach and steam car). So they might not be profitable. People go from their home to one of other sectors and back to their homes (for example home to residential than back to home than shopping than home than work than home than leisure). Make sure you set your lines accordingly. You can click on a citiy’s name to see how much percentage of people of that city are using your line.
The factories supply is based on the demand. If a cities demand is 45 units of cargo than the factory will produce no more than 45 units. Moreover the primary producers (coal iron and oil) will also produce no more than 45 units.
If there is a demand, any industry will increase its production by 1 unit per month. Since the increase in production is slow, it is recommended to first serve the industries with road vehicles until the production is high enough
Industries in Train fever never close, nor new ones appear.