Some subset of those decision are also things which just don't matter, like which side of the road to drive on— the value is in a critical mass of people all doing the same thing more than it is in the merits of either approach.

A lot of stylistic stuff like filesystem layout falls into this bucket.

Bless standard formatters (gofmt, etc) becoming the norm.

Appreciating this lays out the boundaries for the the more borderline stuff. An example of this, IMO, is things like unit testing and mocking frameworks. Most are pretty similar, and offer similar functionality, but perhaps with slight differences in capability or approach to solving common corner cases.

You might have some highly-specific need which demands a particular tool, but it's likely that you're best accepting whatever is most popular in your chosen ecosystem (gtest for C++, nose/tox for Python, etc).