I am so glad to have learned the right word to describe this! I've tried to employ the "drunk looking for his keys under the streetlight" metaphor before but was met with confusion and blank faces. Maybe this is an easier to grasp phrase
It also deals with another matter as a metaphor. It's about doing what's easier but without effect, over what's effective but difficult.
Bikeshedding is about wasting time on non-important decisions.
So there's only slight overlap between the two concepts. The "talk about furniture arrangements while there is a hole on the roof" parent mentions is more apt -- but you can also bikeshed without any more pressing matter present.
The version I've heard is: "rearranging the deck chairs on the Titanic" :)
Probably depends on the crowd. I mentioned this before during a local Python meetup (a few years ago) and I got the same reaction with your "streetlight" metaphor.