To be honest, your situation is unique. As long as your computers don't need to be online to get this data from the trains, fine. For most companies, however, these machines are online and thus pose a major security risk. The security risk should to outweigh the cost of an upgrade every time.
As for a company going out of business, if the company can't afford to keep their software up to date, then they're already on the way out of business IMO. It's the cost of doing business in the first place. If you can't keep up, then you're not doing well. It's only bringing the inevitable to fruition a bit faster.
I can argue against that somewhat as I have experience with similar situation... Working at a place that did manufacturing of electronic components / metal fabrication, the systems those devices ran on were extremely old in terms of OS. There was a machine that ran on DOS 6.2 (in German), some machines that ran OS2-Warp, and several other systems that ran a stripped-down XP.
Those machines cost hundreds of thousands, if not millions of dollars...and the manufacturer of such machines won't just give a software upgrade. They'll force you to replace the entire machine. The machines themselves worked fine...so there was no reason to replace them just for an upgraded OS. The systems were on the internal network, however they were split off on a separate VLAN so they weren't open/susceptible to internet attacks. So sometimes it's not a case of "just upgrade it" because the machinery can't interface with newer software without the machinery itself being upgraded as well.