I try to go through a line with a cashier if I can just to get my support for a human workforce into their metrics, but sometimes I have to use the self-checkout (often because it is the only option after certain hours.) I've noticed that when there is a problem with the anti-theft scale (usually because something has failed to scan because I am moving faster than the weight-check) the sole attendant will just cancel the "bagging alert" from their command station.
I imagine it's impossible to investigate every time the machine stops when one person is "monitoring" a dozen or more of these things.
I've stopped trying to rectify these errors and now just consider it as a discount for me having to take on the work they used to pay someone for. Perhaps the stores see it the same way and the loss is still way less than the cost of employees?