Edit: to be clear, I agree that most people doesn't have siestas and three-hours breaks only remain common in some sectors (retail) and places (small cities). The original article doesn't make much sense, by the way.
A break is generally considered as a short period of time amid an otherwise continuous activity. You don't conceive of night as a break between days, even though you could stretch the definition of the word to accommodate that. Likewise the siesta is not simply an overgrown lunch break.
Doesn't anybody work in those small shops?
> There's a mid-morning and late-afternoon snack
The mid-morning snack is not generalised and the late-afternoon snack is mostly for kids (after-school "merienda").