just because it's a popular idea doesn't mean it's in any way factually correct.
The idea that the government CAN create jobs is the one that's popular. Most people buy the politicians rhetoric about creating jobs hook, line and sinker.
The government can certainly hire people to do work but the money to do so ultimately has to come from tax dollars. This is money that people would have put to other uses had it not been taken from them by the government. Therefore the government cannot create jobs without ultimately sacrificing private sector jobs in the process.
Furthermore, even though the government prints the money, it's the workers and entrepreneurs who give it its value.
It's not that the government never does anything useful but out of all your examples only the "national highway system" has any credibility. Computers? They're a natural progression from the transistor which was developed in the private sector. IBM developed the integrated circuit and would have eventually done so no matter what the government was up to. The internet? I guess no one would have ever thought to hook 2 computers together had it not been for the government. The space program? It was a by product of the cold war which (talk about wasteful spending!) led to a hugely inflated military budget and the current problems we have in the Middle East.
Also, deficit spending is seriously irresponsible and leads to the long term decline of the economy.