They can't. That's why good bra stores carry bras from a variety of different manufacturers.
Getting bras tailored would probably ideal, but it is a very challenging problem. Men's suits have generally the same overall shape, so getting it tailored would usually result in fairly minor modifications to a generic template. However, breasts vary wildly in shape and size - and your torso isn't exactly one-size-fits-all either. I would not be surprised if you ended up needing dozens of "templates", so you'd essentially be working from scratch every time.
Yes, correct. Almost from scratch each time. Maybe there's a level of effort and complexity that I'm not seeing, but it's thin cloth stitched to fit a mold.
Getting bras tailored would probably ideal, but it is a very challenging problem. Men's suits have generally the same overall shape, so getting it tailored would usually result in fairly minor modifications to a generic template. However, breasts vary wildly in shape and size - and your torso isn't exactly one-size-fits-all either. I would not be surprised if you ended up needing dozens of "templates", so you'd essentially be working from scratch every time.