It appears that on most compact digital cameras, the macro mode (flower symbol) works best (or only) when the zoom lens is at the widest setting (comparable to e.g. 35 mm).
What is the reason? Is this even a valid observation?
Each camera has its own arrangements as set by its manufacturer.
Each one works the way it does because of decisions made by its maker and there is no one generic reason that applies. Some cameras work at maximum or minimum. Some at both and some across the range.
eg the Minolta 7Hi (old, still almost wonderful) has two macro settings which nominally occur at max and min zoom BUT all locations in between also work OK.