But familiarity gets more remote as you need larger and larger (or, smaller and smaller) multipliers. It's far more illustrative to say "the volume of a typical gas tank" than "the internal volume of hundred million poppy seeds", even though the volumes are in the same ballpark. For example, https://en.wikipedia.org/wiki/Orders_of_magnitude_(voltage) says that high voltage substations are in 100 kV range and 25.5MV is "The largest man-made DC voltage – produced in a Van de Graaff generator at Oak Ridge National Laboratory" and gives me much better color than a "comparison" with 100 million batteries. (By the way, 100 million batteries stacked together is a bit over the length of one marathon - how many readers could easily tell you that just from the description alone? Much better to measure many lengths in marathons than 10^8's of battery lengths!)
How many have experience with AA batteries these days? How many with 100 million of anything, enough to get an idea of how much bigger that is than one of the thing? Probably all about the same numbers.
Plenty of AA batteries around. And AAA for that matter. At the low end the fancy battery packs can easily be more expensive than what they're powering. Li-Ion is choose only one: cheap or safe.
