The last one isn’t legal and the comparison makes zero sense. A better example would be you’re having a gambling tournament on the street corner and then an undercover cop tackled you while telling you “you’re under arrest”. No knocks help with flushing as well as giving the likely armed criminals less chance to position themselves to murder the cops.
Taylor was actively acting as a drug relay. Her ex would have the shipments delivered to her and then the shipments would be picked up for distribution. This is done this way so that it minimizes loses and charges if someone gets caught, having multiple production houses and people it becomes hard to tie people to a specific case.