Not too well, no. Off-the-rack basically requires good luck and a good eye for how a suit's supposed to fit to find something that works well enough to still be tailored some (rather than extensively, or simply being hopeless) so it'll look alright.

Even shirts, if the sizing's not two-dimensional (trim, slim, regular, loose, or some similar range of cut types aside from just S/M/L/XL and so on—so Large Slim as a size, rather than just large, for example) you're not even gonna get close to an alright fit, most likely. Good dress shirts provide more detailed measurements, but even there, made-to-measure will give you noticeably better fit than off the rack.

In the sense of getting close to a ballpark that can be refined in later fittings it’s basically the job of a tailor. In the sense of being able to commodify it, as I understand it, no.

As well as there being a technological barrier there is also the cultural barrier in that bespoke suits mean something. I actually think the bra thing makes more sense from the POV of offering better comfort.