... The bad news is your in a foreign country that , as a culture , is historically worse. The mordida (or bribe) could be cheap though....
Why is it a "bad" think when people don't have to pay my duty-taxes
As for Mexico : I took a trip to Mexico in the early 1990s, with an immigrant employee of mine. Who was convinced that "treasures are everywhere in Mexico", so a detector will make child's play of finding them
In the months leading up to our departure, I shared with several md'ing club members. And got stern warning of dangers that will lurk behind every corner. Eg.: muggings, food and water that will sicken you, corruption and Mexican jails (if they, gasp, see a detector), etc.... And as I shared each one of these concerns with my guide-host, he would just shrug his shoulders and wonder where-the-heck I'm getting all this from.
We went through the border of El Paso/Juarez, with the detectors in full view. And a border patrol even pointed at them and said something in Spanish to my host. As we pulled past them and onto our travels, I asked my host "what did he say ?". Turns out the guy asked "what's that ?". To which my host had answered "Pasa tiempo" (ie.: "a hobby"). The border guy had just shrugged his shoulders and waived us through.
Never saw any corruption or muggings blah blah . And the food was awesome and fresher than here in the USA it seems. Ie.: they're killing a cow that morning, and you're eating the meat that very night. And the water is straight from mountain spring pipes (we were way up in the Sierra Madres).
I'm sure if you get off the beaten path in the "bad areas" of border towns (seeking vice and such), then sure: You're endangering yourself. Same for wandering the ghetto in any big city in the USA too. From what I understand about the beach resorts in the Caribbean, Mexico, S. America, etc... : As long as you stay in the tourist zones, and aren't wandering side streets and/or soliciting things you shouldn't , that you're ok.