Suppose I'm trying to communicate some group or category, say mammals to a 5-year-old. I could just define or describe the group, but I will probably give examples. Those examples would be typical for the category, such as cow, dog, and mouse.

It would be odd and probably misleading to present unusual examples, such as bat and whale. And it would be odd to use overly-specific examples, such as Jersey cow, well-dressed poodle, or a small gray mouse.

The point is this. Examples can be used to communicate a category. They will usually be ordinary and typical members of the category.

Synecdochal Instances

In contast, when instances are chosen to add vividness, the instances are more likely to be vivid and overly specific. 'Kite string'. 'The County Hospital On Thursday'.

A cowboy speaking about men who work with sheep:

Whatever the category (which is mostly established by contrast), swapping canteens is not a typical member.

So, the point is that when you include the category, there is still a difference between the instances you would choose for vividness and synecdoche versus the examples you would choose to help describe the category.

Did the author need examples? Not really. The category ('mundane events') was already given, and that category doesn't seem mysterious or difficult. Those examples don't increase understanding of that category enough to be worth including for that purpose.

I think the author wanted vividness. And the point is, when you write you should think about whether you are using examples to communicate the category or for concreteness and vividness.

If the author had been thinking synecdoche, she might have constructed more vivid and specific examples. Such as, at least, county fairs instead of just fairs. (She might have been wanted all three having the same sound, but I doubt that's an important issue in fiction books.)

Honestly, no one cares if we call that synecdoche or not. The only goal is to write better. But, as far as I know, thinking synecdoche helps.