A foreign investors is more interested in the answer to the question whether his property rights are protected under the law - than in the availability and accessibility of electricity lines. He can always buy a generator and produce his own electricity - but he can never enact his own laws unilaterally. The second category of infrastructure is the human infrastructure. An educated workforce is as much an infrastructure as any phone line. The last category of infrastructure is the information infrastructure.
Words are symbols - but so is money and computer bytes.
The development of all these infrastructures is intimately linked. They usually develop almost concurrently. They form feedback loops. The slow or hindered development of one of them will disturb all the others. This is really quite easy to understand.