Don’t really agree with the idea that everything should be tendered. Tenders are a poor fit for complex situations where the complete path is not clear. To use your analogy: what if the tender included selecting the building to tear down as well as demolishing it? Without further specification, the winner of the tender could have an abnormally low price, be incentivized to pick the easiest building to demolish, and leave the rubble on site because you forgot to define what demolish actually means.

In coding terms: if you can do it waterfall then you can probably tender it, otherwise I’m not so sure.