When people hear the term money laundering today, they envision the most evil of acts, in which gangsters process satchels of cash through a fabricated company to show it as business revenue. Words and semantics are very important in this post-9/11 world, and as far as creating a negative connotation, that parlance has been extremely effective.
At its essence, money laundering is the act of concealing money or assets from the state to prevent its loss through taxation, judgment enforcement, or blatant confiscation. However, as the late J. Orlin Grabbe wrote: "Anyone who has studied the evolution of money-laundering statutes in the U.S. and elsewhere will realize that the 'crime' of money laundering boils down to a single, basic prohibited act: Doing something and not telling the government about it."
Protecting one's wealth is interwoven with the history of trade and banking which has existed since the dawn of commerce. Sterling Seagrave's Lords of the Rim describes how some 2,000 years before Christ, merchants in China would hide their wealth from rulers who would simply take it from them and subsequently banish them. This concealment involved moving the wealth and investing it in remote provinces or outside China.
Part myth, part rumor, the plausible tale of Mafia gangsters running huge amounts of cash from extortion, prostitution, gambling and bootleg liquor through existing Laundromats accounts for the phrase money laundering.
Also during this period, Al Capone was convicted in October 1931 for tax evasion, which is what earned the prosecutor's conviction rather than the predicate crimes that generated his illicit income. Capone's episode inspired Meyer Lansky, the mob's accountant, who structured elaborate international and Swiss financial facilities for safely securing money and vowed never to suffer Capone's fate.
Lansky is credited with designing one of the first real laundering techniques, the use of the "loan-back" concept, which disguised allegedly illegal money within "loans" provided by compliant foreign banks. The money could then be justified as revenue and a tax deduction for interest expense obtained in the process.
Without any method of tracking cash or bank activity, Congress passed the Bank Secrecy Act in 1970, heralding the age of transaction reporting, including the Currency Transaction Report (Form 4789), the Report of International Transportation of Currency or Monetary Instruments (Form 4790), and the Report of Foreign Bank and Financial Accounts (Form TD F 90-22.1). In the United States, the Money Laundering Control Act formally made money laundering a federal crime.
Internationally, the elements of the crime of money laundering are set forth in the United Nations Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances and Convention against Transnational Organized Crime. Also, the Financial Action Task Force on Money Laundering, founded in 1989 on the initiative of the Group of Seven industrialized nations, is an intergovernmental organization whose purpose is to develop policies to combat money laundering and terrorism financing.
The other side of that argument would be Bitcoin (wiki it). Nothing regulated there, therefore no potential crime regardless of the source of the finances. But your example, "It's like buying a drive-thru donut in a stolen vehicle" is not accurate. The metaphor would be more accurate as "It's like verbally assaulting a drive-thru donut employee in a stolen vehicle." Both parts are against the law.
Although to be fair, in this age of burgeoning crypto-currencies, I could easily support a thesis on the theme of money laundering laws being increasingly worthless. The intent underlying the law, however, remains relevant.
I support voluntary financial transparency.