The third environment is a large business maintaining services long term. These services do not change in fundamental ways for well over a decade and they make a shit ton of money, yet the requirements never stop changing in subtle ways for the clients. Bugs pop up constantly, but there's more than enough time to fix them the right way as outlined by their contract where expectations have been corrected over the years. There's no choice to do it any other way. The requirements and deadlines are firm. Reliability is the priority.
These are the stable businesses of the broader working world and they're probably what will remain after AI has driven the tech industry into the ground.