Apart from cleanliness and other operational issues, I think there are at least two other questions: how much does it cost to run a railway and how much should people be asked to pay?
The very poor - and you know exactly who I mean - couldn't afford the old prices anyway. They "Ride the Rails" and enter and leave the system by uregulated means and I presume the authorities turn a blind eye on purpose. The people who will be hit most badly will be those, like - but not limited to - the domestic cleaners in the other BAExpats thread who barely earn enough to get by (and in all honesty probably don't earn enough to get by) on current prices. I think it is urgently important to see that these are not the people who end up subsidising the system.
How much does it cost to run a railway? I'd be delighted to be corrected on this but as far as I know there is no country in the so-called First World that doesn't subsidise its rail system for the social benefits that brings. Amtrak in the USA receives government subsidy, doesn't it? In the UK, those lines that have not failed under private ownership and been brought back into state ownership are still subsidised by the state (although their private shareholders still received their dividends and bonuses - how does that happen?) In the UK I only know of two rail routes that receive no subsidy and they are high-priced, short-distance convenience-oriented airport lines.
So, it's going to cost about ARS25,000 to ride from Constitucíon to Mar del Plata. Getting some quotes from Google that appears to be about one-third of the current airfare with Aerolineas. The equivalent distance on Amtrak is about the same as the line from Washington DC to New York where the fares (again, from Google) range from 150% to 300% of this sum. In the UK, (again on a system subsidised by the state) passengers between London and Lancaster (again, roughly the same length of route) will pay between 350% and - wait for it - over 1000% more for their journey.
So.. how much does it really cost to run a railway? How much should passengers pay? How far should the state intervene?