the problem is/was with pricing.
they priced it on par, or even a little more than regular Valvoline. as others have said, there is a public bias that "used*" oil is inferior, and it should therefore be cheaper.
in some parts of the world it is. If you go to cananda, their supertech(now called something else) oil, is/was a fully re-refined product of safety-kleen. you could get a 5 gal bucket for ~$40.
Safety-Kleen does have a re-refined product line here in the states, 2 actually "America's Choice" for Govt Fleet Vehicles, and "Eco-Power", which they only sell to shops. I've asked, and they have no interest in mass marketing it/retail sales, they just direct you to a shop "near" you that carries it.
so, I did that a few years back, found a shop that carried it, contacted them to see if i could buy a jug off of them, they said yes, i went to collect, and the counter monkey looked baffled, ended up charging me $40 for a 5qt Jug.(basically what they would have charged for an oil change)
*I know it was re-refined, and just as good as the first time around, just trying to illustrate a point