I don't think I can be 'exact' but perhaps your expectations are too high if you think it is realistic to be able to apply for a job working on railtours.
There are many volunteers who would like to be paid to work railtours and would be higher up in the 'pecking order' in the unlikely event that such positions were created. If you want to work on railtours, you have to volunteer, and even that can be difficult to get into. For example, there were many people who have offered to volunteer for Retro Railtours, and most have to be declined, simply due to the high volume of requests.
There isn't any money to be made by working on railtours, and operators of railtours do well to break even, so tough is the market (and that is with many people volunteering, for example I don't get paid to do to the Retro website, neither would I ask to be).