Pretty sure professional US bakers also work by weight. It’s much simpler and more reliable, especially when you have to deal with aerable dry goods (flours, powdered sugar, cocoa powder) or solids (butter).
- some recipes can be very finicky regarding ratios,
- e.g. different flour types can vary quite drastically in density
- you can e.g. easily reduce the volume of a flour batch by at least 15% by pouring differently (or simply bumping the container a few times)
going by volume alone still works for most recipes and is quite frankly as easy as it gets.
Going by weight alone also is not entirely scientific though (e.g. moisture of raw ingredients is usually not exact/controlled). And flour can behave differently, based on batch or type, even if you get the weight perfectly right.
So most bakers have their recipes "dialed in", i.e. they have a feel for the right texture, how the dough behaves, how to adjust resting times, etc.
