If a train fails, at worst that will happen is it will stop. When a space station fails, the worst that will happen is everyone inside dies.
In addition, a space station is far more expensive, and it may be simply too expensive to still maintain old technology. Ideally, at some point, one will replace it with a newer, more modern, space station. Which will both be cheaper, and allow more, novel, science to be done. Although I don’t know if there is any plan for that.
I’d like to see a space station with a rotating ring, that generates artificial gravity through centrifugal acceleration.