> I can't think of any good reason to use volumetric measurement in cooking

A good reason is because you rarely need exact measurements in cooking (vs. baking), and it's easy to eyeball approximate volumetric measurements, especially with help from the known volume of a container; also because many recipes need quantities of some ingredients (most frequently water) that would require a much larger and more expensive kitchen scale than most people would like to keep.

Small quantities under a tablespoon or 10ml by volume can be quite challenging to weigh, and is much easier to fill up a fixed size tsp/tbsp measure. If your ingredient is a commodity and has a known density ahead of time (water, olive oil, salt, whatever) its mechanically simpler. There are also times when you can't measure into your cooking container directly - maybe it's hot.