I agree that there is no such 100% drug free but i can be lessened the volume of drugs in a country once government have a good technology on detecting drugs and preventing to enter to the country.
I doubt that. Some of the countries with the worst drug problem are those having the best technology. Examples are the United States, United Kingdom, and Italy. You are ignoring the fact that technology can aid the other side as well.
It can't be lessen by technology alone. As Sithara said, it could aid the other party too. If we want to make our country drug free, focus first on the reason why those drug addicts become one. Concentrate the technology in improving the economy and the life of the people.
Instead of killing them day by day including those inocents. It could even create a mind set to people that the government is an oppressor.
None of the above you Duterte will not do. He went the other way. For it is much easier to kill the drug than to raise the economy. This is a typical the signs of dictatorial power. I am sure that life in the Philippines gets worse.