That said, a tailor will make you pose properly and not slouch or droop your shoulder, so they would take better measurements. Presumably, SW could correct for bad posture as well.

Manufacturing at scale is currently impossible.

Tailoring is basically robotics' worst nightmare: input material with varying characteristics from batch to batch, delicate materials, multiple different motions and tasks, a non-reducible movement and orientation space (e.g. sew a hem along a curve), and a complex mapping between physical tasks and end result (different stitch on seam = different motion).

We'll get there (and if it weren't for low cost labor, would already be there for t-shirts). But it's really hard.