One reason for this phenomenon is that the people who are being raided don't know who is doing the raiding. Even if the cops or DEA agents identify themselves, how can the occupants of the house know that they are genuine law-enforcement agents rather than killers posing as law-enforcement agents? This is especially the case if the people in the targeted house have a connection to the drug trade. For all they know, the raiders could be members of a rival gang coming to wipe out the competition by posing as law-enforcement officers.
Thus, in a drug raid the occupants of the house must make an immediate life-and-death decision. If they decide not to resist and it turns out to be the cops, the occupants stand a good chance at surviving the ordeal. But if they decide that it's a rival gang and decide to resist with force, they will all be massacred if it turns out to be a genuine drug-war raid. On the other hand, if they decide to submit and it turns out to be a drug-war rival, they will be massacred by their competitors.
Would gangsters really pose as law-enforcement officers as subterfuge to enable them to kill their competitors? Well, let's go to Haiti and find out. That's where the president of the country, Jovenal Moïse, was recently killed by a team of assassins.
According to the Miami Herald, the assassination took place in the middle of the night, when the assassins raided the president's home. The assassins claimed to be DEA agents. According to a video that was taken, one of the assassins was yelling in English over a megaphone, "DEA operation. Everybody stand down. DEA operation. Everybody back up, stand down."
It sure seems like a smart strategy to me. And there is absolutely no reason why it can't be employed here in the United States against competitors in the drug trade.