That's not the goal. Consider: you have bills with serial numbers known to have been stolen during a bank heist, and you want to exchange those bills with ones that are not known to have been stolen during a bank heist so that the feds don't pick you up for using them. In that case, the jar helps you do so, and that's money laundering. If other non-bank robbers participate in the jar knowing that you are doing this, they could also be charged with money laundering.

If you have $100 in $10 bills from an unknown source and suspect that it might have come from illegal activity, stick it into a jar where 100 people have each put $100, and then pull out $100 at random in an attempt to disconnect from its potentially illegal nature, that is called money laundering.

If you know that your money is legally obtained and put it in the same jar (for privacy purposes, for instance), you probably know that you are facilitating somebody else's money laundering (but are unlikely to be charged for it).

If I want to take my completely legitimately obtained money and obfuscate its source by putting it in a pool with people I have no knowledge of or connection to, I don't see why it should be assumed that I believe these people's intent is to launder the proceeds of some sort of illegal activity and not other people like myself. I think it's even more of a stretch to say that I would know that I'm facilitating someone else's money laundering in that case. There are completely legitimate reasons for wanting to obfuscate one's transaction history, just like there are legitimate reasons for wanting to use an email aliasing service, VPN, etc.

What would those legitimate reasons be?

I may not want one entity I pay to know every single other entity I pay/paid or received money from, in what amounts, and when.

This could be for personal reasons--perhaps I'm purchasing health-related products/services...or something less high-minded like sex toys--or for professional reasons. I could be running payroll, paying suppliers, etc. and don't want everyone, including my competitors, to have easy access to all my financial activity.

you don’t want people to know you’re into femboys? or really anything else? like you’re seeing a therapist?

This whole scheme only works if no one knows you put money into the pot. It works for crypto because the receiving account can be created anonymously, disconnecting that account completely from the original source.

You are only unlikely to be charged for it because the scale is small

The point is if you mix cash with the intent to conceal the source, that’s illegal. The law is about intent

Is it illegal in all cases? Or only in cases where the source of my original money was illegal?

If my source of money is inconvenient or embarrassing but legal, it’s not at all obvious to me that tumbling cash is illegal.

The limited research I did suggests it’s illegal iff the source of my original money is not legal.

This is what the article is about. It’s a good read. Very clearly explained.

But the arguments against coin mixers basically claim that if someone wants increased privacy that means they're criminals, and so all coin mixing should be illegal.

Yeah, the key “innovation” of crypto tumblers is that funds end up in a different wallet than they came from. If the tumbler just spat the money back into the wallet the money came from, it wouldn’t be very useful.

But I suspect that as the accuracy of the analogy goes up, so too does the inherent sketchiness to the reader, which is probably not what the author wants.

> If the tumbler just spat the money back into the wallet the money came from, it wouldn’t be very useful.

That's not necessarily true. This coinswap proposal [1] aggregates a set of self-spends (wallet spending a balance back to itself) and in the process obfuscates the transaction graph.

[1] https://forum.grin.mw/t/mimblewimble-coinswap-proposal/8322

The analogy is just to say that you should be allowed to put legally obtained $100 in the mixing jar.

Obviously illegally obtained money is illegally obtained regardless of the number of hoops you go through to hide it.

Scale that to 10 people each putting 10$ in and then each taking 10$ out. Now when police comes they tell they got money from the jar...