Think about it as a measure of value - a very high value of inputs went in; the tickets have a low price because what was built has no great value to the riders

Think about it as a measure of value - a very high value of inputs went in; the tickets have a low price because what was built has no great value to the riders, so you can't charge them more or they won't travel. Now if the government is subsidizing something of great value fine - child care, education, research, preventative medicine, all that's fine 'cause that produces great value over time. On the other hand, if you keep using up a big pile of inputs to produce a smaller pile of outputs or nearly-useless outputs, real wealth shrinks even though the economy is churning away producing apparently good numbers re economic activity. Hiring people to tear down every structure in China would also produce good economic numbers while reducing wealth. Roads to nowhere do pretty much the same thing, just more slowly.