This is only because most recipes are incredibly imprecise. Chefsteps have gram measurements for almost everything, baking or not, and have a scaling tool built into their recipe view. It's incredibly useful.
At a certain point you run into physical realities of living, growing things. You can use ratios to make homogenized items (mashed potatoes or sauces or caramelized onions or sausage). But even if you had two chicken breasts of the same mass they'll need different amounts of sauce or coating since they'll have different surface areas, and different cook times since they'll have different volumes.
I think any recipe for roasted vegetables has to be by volume of the chop/dice fwiw. There's lots of ways to chop carrots into 20g chunks, but they won't all cook well or evenly, so a 1/4" dice is what you'd call for (even if you call for 600g of carrots)
One problem with cooking is that your pans and heat transfer do not scale. So you cannot just arbitrarily scale up/down recipes, even if you take precise measurements. The result may be way too watery or dry, for example.
I think any recipe for roasted vegetables has to be by volume of the chop/dice fwiw. There's lots of ways to chop carrots into 20g chunks, but they won't all cook well or evenly, so a 1/4" dice is what you'd call for (even if you call for 600g of carrots)