It seems to be about both taxes and making yourself not traceable to a crime (or the latter is a side effect of the former, since making money appear legitimate

It seems to be about both taxes and making yourself not traceable to a crime (or the latter is a side effect of the former, since making money appear legitimately earned will of course unlink it from any crimes as a side effect/prerequisite). Look at the definition here and tell me it doesn't sounds like a mixer: https://www.fincen.gov/history-anti-money-laundering-laws https://www.fincen.gov/history-anti-money-laundering-laws Similarly there can be unusually high tax (like the 75% in Poland) on undocumented income but if that money could also be traced to a bank heist or drug deal as well you would be in much more trouble than just that tax. As for USA's (un)usually far legal reach, strong extradition agreements, etc. - that can be up for debate. But money laundering itself (especially when starting with stolen funds) is hardly legal anywhere and mixers seem to fit the definition of laundering at a glance if you consider Bitcoin a currency, it's typical case of law not catching up with the technology and legacy laws being reused instead.