I'm a cashier/guest service/hardlines/potential GSA at minimum wage. If I leave, Spot will go on and it will be another day....top performer or not.
Obviously this is true. The point is, they want to continue store operations with as little interruption as possible. Let's say you - the GSA - suddenly walked out in the middle of your shift one day. The front lanes would struggle at least somewhat. They would have to take time to schedule other people, which would in turn piss those people off. More than likely, they won't be able to cover 100% of your shifts because they didn't expect you to walk out, which creates at least a few days of head ache for them.
Now, are you going to impact anything outside your workcenter? Probably not. The fact is, you still cost them money, time, and frustration in some small amount. This is where you see how greedy corporations are. They don't even want to suffer that tiny little .01% bit. That's why they create a penalty if you walk out on them. At Target, that means being banned for life from ever working there again and possibly bad references to future employers.
Now - answer me this - if you TRULY could walk out without causing any problem to them what-so-ever, then why would they intentionally create deterrents (black listed for life, bad references, etc.) to discourage people from doing that? The answer is - they wouldn't do that if it truly caused them no problems at all. You may be a peon, but you still have at least some impact. That's why they make sure to "punish" you by blacklisting you if you do it. If you truly didn't cause them any trouble, then why blacklist you?
Now let's look at how unbalanced all of this is. You walk out without notice one day. You cause them a minor .01% problem in the company. What happens? Banned for life and possibly get a bad reference hurting future employment.
On the other side of the coin, what happens if you walk in one day and with no notice they tell you that you are fired? Not a damn thing happens to them. To you? Your life can be potentially screwed. Your kids might not eat, you might go homeless. In other words, they can screw up 100% of your life with no consequences to them. You walk out on them without notice, though causing them minor .01% problems? They make sure to punish you in the last ways they can.
That is how screwed up and unbalanced corporate america is today.