Professor Blackburn then gave apparently simple examples of code in PHP which give unexpected results. Steve went on to discuss the cost of inefficient computer programming languages which use more processing power and result in increased carbon emissions and global warming. He claimed that problems with languages occur because they involve difficult concepts and are difficult to engineer. Decisions made in language design get "baked in" to the system. This did not seem to me to be a new insight, when designing any new system trade-offs need to be made and have to be lived with.
An example is the Contact Wire System for the Gotthard Base Tunnel. At the time the tunnel was designed an over-head wire had to be used to supply power to the trains. Today an alternative technology is available which would allow the tunnel to be smaller diameter, saving many millions of dollars. But at the time the tunnel was designed the new technology was not proven and so could not be used.