Ethical fields that use AI for other reasons than mining personal data?

I am going to be working on a ML + expert system + genetic algo hybrid for the UK's Network Rail, specifically its research organization. Managing delayed trains is a big issue - the trains impacted by the delayed train can be dealt with more or less, but trying to figure out the best course of action to deal with the trains delayed by that set (and so on) is essentially a NP hard problem. Competing cost functions to optimize etc and the traditional methods are not as effective anymore due to infrastructure changes, more trains, more passengers, etc.

There has been a lot of academic research, but only in the past few years have transport companies been investigating and implementing more sophisticated solutions (Japan is of course a decade ahead of the West).

So what you are looking for is out there, but you have to get away from the IT industry. Look for jobs involving IT that involve supporting businesses / business sectors that are not primarily IT or consumer focused. I feel your pain - I got tired of only seeing companies focused on marketing and all that sort of thing. This is more a research contract to investigate the feasibility, so perhaps you should find a university and do some networking.

Finance is another sector to look at, but I don't know about the better world aspect of that...