I mean, trains -do- need tracks. When they don't, they become cars/buses, for all intents and purposes.

As to prices, from a quick search, tracks are more expensive per mile, but I didn't see anything talking about maintenance cost. Hopefully these sources are reliable:

• 3-4 million USD per mile (~2020 prices) for train tracks, assuming flat rural terrain - https://www.freightwaves.com/news/commentary-do-you-want-to-build-a-freight-railroad
• ~2 million USD per mile (2014 prices) for highway, assuming flat rural terrain - https://www.strongtowns.org/journal/2020/1/27/how-much-does-a-mile-of-road-actually-cost