https://www.indochino.com/suits/fit
That one is a "measure at home" affair, but I've also heard tell of ones where there's a pop up at a co-working space or whatever, and you go get measured, pick your fabrics, and get the shirts in the mail a few weeks later.
Cost-wise, it's definitely more than getting them at a department store, but it's not ridiculously more. Think like 2-3x rather than 10x.
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.
The sizes vary within brands themselves.
Traditionally the solution was to get a tailor take your measurements and make a pattern for you and cut from cloth to make you a garment. Obviously, in today's day and age, that gets a bit expensive for most people.