I would assume we do not have the intelligence, nor the ability to keep tabs on what and where everyone and everything is at once.
Starting in the jungles and looking at just coca.. we will leave heroin production out of this.. there are going to be thousands of super remote locations buried deep inside the jungles, well hidden, and spread out across numerous countries, countries with different tolerance levels to our presence (Bolivia is extremely cold to our Coca eradication ideas).
Deep in the mountain jungles in remote valleys and steep hillsides there are coca farms, there are also coca processing plants in the same geographical proximity that are very mobile, and very easy to pick up, move or reestablish. All you need is a pit in the ground lined with plastic to spread the leaves across, and a few chemicals to process it.
The logistics of pulling this off are mind boggling, we have been there trying to do exactly what you claim, we have been engaged in a long term eradication campaign in S. America to no avail, it is a logistical nightmare, and the production facilities are super mobile, and the crop is extremely widespread and culturally ingrained (thousands of years ingrained).
Even if we had permission to enter these countries and decimate their fields.. and yes their economy (like it or not it is their economy), the cost in manpower resources and money would be huge to accomplish this, and even IF we got all of it, it would be back again the following year awaiting our dedication to rinse and repeat. We have been attempting to do this for a long time, to no avail.
It has been estimated that there are 100,00 members/soldiers in the carious Mexican Cartels , so umm you were saying about manpower? Sure we have technology, but in a guerrilla war? conventional armies and our technology are ineffective in a war with this army, we cannot hope to identify all the players, and it is in their interest to remain hidden. They are in the cities of Mexico.. we may get away with drone rocket strikes in the rural areas of Pakistan, but you really think this will go over well in the middle of downtown mexico city or Nuevo Laredo? You want concerted strikes on their activity centers, their activity centers are on the streets of Mexico.. I highly doubt Mexico will sit by and allow us to come in and risk that kind of Collateral damage.
I could continue.. but to do what you propose and even dream of having an effect it would take an IMMENSE amount of dedication and resources, we would have to invade, occupy, and engage in guerrilla war in numerous countries on the scale of our current presence in Afghanistan.
Never mind that the next year there will be a new crop and (provided we killed off every aspiring Mexican foot soldier, MS13 in Guatemala, cartels in Columbia, ect, ect.) there will be some group that will step up somewhere to fill the void.. there is too much money to be had, and too much poverty in the world for people to not risk getting killed for such lucrative rewards.
Quite frankly.. the cost of eradicating the problem is too high, we as a nation will never ever want to pony up and pay the full cost (it is bad enough that ~1 trillion dollars has been dedicated to this war already) in manpower, resources, money, and self policing of our country to eradicate the problem,
We don't need to, there is a much simpler, much cheaper way to go about it, a way that does not relinquish control to nefarious elements and the black market which is fueling the Mexican violence, but we do not have the stomach for that either and many see it as giving up, or as caving in to a drugged fueled nation, when in reality it is just picking our battle wisely, and starving out and eradicating the criminal problem so that we can then focus on dealing with the drug problem.
edit to add link to cartel number estimates:
EXCLUSIVE: 100,000 foot soldiers in Mexican cartels - Washington Times