> There is a long history of people deliberately selling themselves into slavery.
"Selling yourself into slavery" is a contradiction in terms. Willingly exchanging labor for compensation is not slavery. It's just an attempt to frame things in an inflammatory way.
Suppose that someone kidnaps you and forces you to work without compensation for the rest of your life. Suppose that you willingly agree to sign onto $250K in student loans that can't be discharged in bankruptcy and which you will never in your whole life be able to pay all back. Is agreeing to work for someone your whole life if they put you through college more like the first one or more like the second one? Clearly the second, I think, but then we see people calling it "selling yourself into slavery" on one hand and the government explicitly subsidizing it on the other.
Agreeing to either of those sets of terms is, of course, problematic. But the problem isn't caused by someone being willing to offer those terms, it's caused by people being desperate enough to accept them. And you can't solve that by limiting their alternatives to whatever even worse option that caused them to choose the objectionable one to begin with. You have to add better alternatives, not remove existing ones.
> In addition Walmart spends considerable effort and money lobbying governments to undermine basic worker rights and protections.
You say "undermine basic worker rights and protections" while they say creating jobs for unskilled workers who would otherwise have to rely fully on government assistance.