As already mentioned, the method that always work for me in hard mode is to build an intercity tram line between well positioned cities at the beginning, then add more tram connections between nearby cities. The frequency should be no less than 60 seconds (a lot of trams are needed starting in early epoch).
With this method, after 5/10 years you will have a stable income of 400/600k per tram line, and soon you will collect enough to build your first railway line. Be careful, to make the railway profitable, it should connect two hubs that have already trams connections to other cities, and at least a population of 4/500.
Soon, you will have a stable income and you can expand your network further, but be careful with railways, because if you don’t plan them well, they become profit suckers.
However, I agree that the game economy would benefit from a rebalance, but in my opinion the rebalance should not decrease the maintenance cost, that add the necessary challenge, but increase the trains revenues by 30/35% in comparison to trams and buses (as in real life, train tickets are always most expensive that tram or bus tickets), because at the moment it really doesn’t make any sense to build railroads in the game, trams are just more profitable. For reality purpose, building costs and maintenance could be increased too, because the vehicles maintenance and prices are ridiculously high compared to structures cost and maintenance.