A senior engineer obviously needs (and knows how to handle) considerably more access to their workstation and company IT infrastructure than the average employee. On the other hand, I've occasionally read complaints from IT security types about engineers being way too eager to install sketchy stuff.

There's some truth to those complaints. I might need to try out several libraries and tools to see what works best for a certain use case. Is that new one with 15 stars on Github actually safe? Are all of its dependencies? How many developers perform a task like that in a sandbox? How many of those perform a thorough audit before taking it out of the sandbox?