Basic detective work is a relic of the past. The informant doesn’t identify themselves. Strike one on credibility. The cops made no apparent effort to gather their own intel on the supposed criminal or the target premises. Strike two. They even reject counter intel on the subject from a relative who appears in person to vouch for him and offers to enter and contact the subject. Strike three.
Did they even try calling the guy on the phone? Wouldn’t that be step one in a potential hostage situation?
I assume on point 3 they wouldn’t send a civilian in because of the risk. Obviously it would have been better if they called, but I guess they wanted the element of surprise.