There were four transcontinental railroads built across the western US between the Civil War and 1900 , five if you say North America. The Union Pacific, the Northern Pacific, the Great Northern and the Santa Fe/ Southern Pacific, and the Canadian Pacific. Each one got HUGE subsidies from the government in both land and money. Most went broke numerous times and corruption was far more rampant than any recent period.
Synthetic rubber was essential for fighting WWII, as the Japanese took over Indochina. It was developed with government money. Aircraft and air transportation was subsidized by the government in many ways.
Individual projects need to be judged on their own merits, and there is always the understanding that not all will be as successful as proposed. There will always be some failures. But to say that the government should not subsidize ANYTHING is insane. Were it not for ARPANET, we would not be having this discussion, not here, and almost certainly not anywhere else.