To put this into perspective, China's high-speed rail project in Indonesia connecting Jakarta and Bandung (a distance of 143 km) at a speed of 350 km/h was completed in just four months at total cost of $7.3 billion.
This line has seen an impressive number of passengers, with approximately 2 million people utilizing the service.
High labor costs due to too many unions, usually.
(This is a lie: the US has lower labor costs and union participation than other countries that have trains. But it's the answer I see most.)