I tried volunteering first at a standard gauge restored railway, and then at an industrial railway & transport themed site, looking forward to getting my hands dirty and with fond memories of metalwork and engineering at school. In both case I was stunned at the unprofessional poorly managed way that new members were dealt with. In both cases I was given an initial job and than had to spend hours finding somebody to allocate my next job. Those encountered either ignored me, or were downright rude and ill-mannered. I have a memory of sitting in a 'lodge' at lunch with a room of overalled engineers and not a word was spoken. All long miserable faces. Then one mumbled "I come her to get away from the wife". I thought to myself '"the wife" is well rid. Perhaps if you have skilled hands you have no interpersonal skills and are best left stuck in an engine shed or machine shop. In both cases I walked off the site mid-afternoon never to return. All this happened late 2010 and nobody has ever followed up why I never returned.
Then I discovered a restored railway that offers a free day to prospective volunteers witnessing most aspects of how the railway operates. A grand tour of all the major operating aspects including a ride on the railway to visit other stations and workshops. At the end of the day a discussion to establish where you might like to work. Professional friendly efficient and effective. As a result I am about to complete my first full season as a guide.
SO... it's not so much about the railway, but the people and the manner in which the operation is run.