I'd say all the Civil engineers who continue to spec steel do it for well-established reasons.

Steel is just so hard to beat in so many applications. Even for the average road bicycle, surprisingly. Because steel can tolerate more flex than things like aluminum/titanium/carbon fiber. So other materials require different designs. In the end, the average street bike in steel or aluminum can often weigh the same, depending on the design choices (not specialized bikes, where different compromises are made).

Like so many things, when used as designed in concrete, steel is just fine, and I assume meets the cost, availability, industry knowledge, etc, goals.

Makes me think of "don't remove a fence until you know why it's there". Every year upcoming engineers do tests during their education. If a different material was a better choice, I'm sure a research arm of a university would present it.