Fascinating stuff, and I feel like I just took a class in tailoring… thx!
You’re right, the skill and labor are the biggest parts, though no doubt Amazon’s sheer size will still have some impact. But it also seems kinda unlikely that extremely short runs or lotsa custom “one-off” garments will ever be practical. And even simple t-shirts are obviously not as easy to reproduce as, say a 3D-printed mug (yet)?!