R D S wrote:
Can anyone explain why button cells are used in things that would take a
bigger battery or several?

I'm forever changing the one in our bathroom scales.

Lithium primary cells are 3V, whereas alkaline are 1.5V. You'd need
something like 2x AAA to provide the same voltage. They would be bulkier
and more expensive to house (need a battery holder with springs and such,
not just a PCB clip).

Lithium manganese cells also have a relatively flat voltage curve, which is
useful for metrology (the cell voltage stays constant until ~80% capacity
has gone, meaning the scales can stay in calibration without much effort).

Theo