Maybe it will, but it's sure as fuck not there right now.
I repeat, every time you do the self-checkout and the machine fucks up one time? You just lost whatever time you would have saved checking out at a checker. But the machines usually fuck up either multiple times (like the scale or the bag area glitching out) or they fuck up so hard I have to call an attendant (locking up, freezing).
I won't argue stores would rather have more self checkout and fewer employees. Obviously they would. I'm just saying it's a "solution" that sucks for the shoppers because the machines are fucking awful.
Also, even if the machines get better, stores have to spend money to upgrade their technology, and there's plenty of stores still using cash registers from 20+ years ago, just because they don't want to spend money. Even if better checkout machines exist, stores still have to put down the cash to install the better machines.