I have certainly heard of such arrests in Mexico. Off hand, I can’t name one. Here’s the advice given to USA travelers to Mexico from the US consular:
Arrests
1. US Laws DO NOT apply in Mexico. The American Citizen Services Unit cannot provide protection or remove you from jail. Nor can it act as your attorney.
2. The American Citizen Services Unit can visit you in jail and provide a list of lawyers without recommendations.
3. TheAmerican Citizen Services Unit will visit American prisoners to asses reasonable treatment - within the norms of Mexican jails, and where mistreatment is believed to have occurred, file a Protest.
4. Mexican Law is Napoleonic, and thus quite different than what US Citizens are used to. Mexican Law presumes you are guilty until proven innocent.
5. Advice: avoid problems with the Law. Especially avoid illegal drugs and people likely to be associated with drugs.
http://www.mexconnect.com/mex_/usconslg.html
>>I have certainly heard of such arrests in Mexico.<<
The trouble is that the Mexican police (with some exceptions) are so corrupt that many abuses are not reported. In some cases, if an American is involved in an accident with a Mexican driver, the American is automatically guilty. (Yes, Mexicans might get railroaded in the USA too.) I met an American who spent months in a Mexican jail before some family member paid a bribe. It’s often better for an American to pay the bribe, because
1) That is the only way out
2) No criminal record. But Mexico’s records are kind of shaky anyway, so who knows if that would make any difference. I suppose that Mexican officials might make a determined effort to keep records of those who refuse to pay bribes.
WRT Mexico, I don’t think that US citizens always receive just treatment. OTOH, if the USA does not “review” (whatever that means) the cases of Mexicans-on-death-row-who-didn’t-talk-to-the-Mexican-Consulate, Mexico could retaliate by treating US citizens even worse. Still, in my view, to give up our sovereignty in fear of Mexican retaliation would be like negotiating with terrorists.