Hacker News Reader

In Belgium, there are 'civil engineers' that know nothing about the construction of roads buildings or bridges, but are specialised in electronics, computer science, thermodynamics, ... .

In the case of Lemaitre, he was studying this: https://en.wikipedia.org/wiki/Mining_engineering

In the US/UK civil engineering is often taken to mean constructing buildings (very roughly, in a nutshell), whereas other countries (in particular continental Europe) use the meaning that you quote. So you can have a Belgian civil engineer who specializes in theoretical physics, and knows more about the Higgs boson than about "traditional" engineering topics.

I’d guess to differentiate the civil / uncivil dichotomy from the civil(ian) / military dichotomy.

That said, I feel that civil engineering is fairly widely understood to be a subdicipline of engineering.