That's because the chain can have multiple ways to money launder and I'm not going to list them all. The second hand car dealer was provided as it's a quick and very simple example. The example can be made more complex easily.
I'm pretty certain this started out as a pedantic correction that money laundering isn't about creating a fake legal explanation... I even said I was being pedantic.... I've since explained how money laundering can happen without fake legal explanations, and I stand by my pedantic correction!![]()
Well if your only example is someone paying for low-value goods with cash then I don't think you have explained anything here even if admittedly trying to be pedantic. As mentioned before a motivation for money laundering is because having large amounts of cash or assets with no explanation for where it came from is risky. If you buy a large number of cheap second-hand cars you still have a large amount of assets with no explanation for where they came from, you're missing the laundering bit - how are your assets now "clean"? They're not AFAIK.
Buying something with cash earned from crime might well constitute an offense under money laundering legislation however doing so in itself doesn't necessarily "launder" any money.