I don't know anything about the situation in Russia, but that definitely happened in Northern Ireland.
It's not the difference between anonymous tip and non-anonymous tip, but between anonymous tip and no tip at all, because no one wants to be punished for doing the right thing.
Remember Richard Jewell from the Atlanta Olympics?
They aren't wrong. Federal circuit judges and the Supreme Court have ruled that police have no duty to protect anyone in particular. They routinely suffer no meaningful negative consequences for serious failures in their work, including killing people who are unarmed, not resisting, and not suspected of committing any crime.
And after the Boston police screwed up the Mooninite promotion for Cartoon Network in 2007... well, it's enough to say that Turner had to pay for and publicly apologize for the police response to their fancy LED-illuminated handbills--absolutely Kafkaesque.
If I ever find a suspicious package, I'll certainly alert bystanders to retreat. I'll pull the firm alarm on my way out. I'll call the firefighters. I'll call the local newspaper and television station newsrooms. I might even call the triage nurse at the nearest ER. But someone else can be the one to call the cops.
Now, for a second, imagine that it really happened. And you're the official who decided "no, we will not act on this". And this decision is in the records. Does this situation look good to you?
If you look at a similar case, in US. SWAT-ting can be anonymous and can destroy lives, the assymetry of the tips and the resources destroyed by a false tip is unacceptable.
The same way for a bomb threat, the officer should act by requiring identification and guaranteeing that it stays private as long as the bomb is real.
Those officials then have to get reelected.
That's usually easier when your opponents can't make legitimate-sounding claims that the policies you've instituted led to a bombing.
IDIOT ANCHORPERSON COVERED IN MAKEUP: Breaking News: We've just learned that the bombing that killed 152 people in the Podunk Shopping Mall today was known in advance to the police, but they did nothing to inform the public! Now to our reporter on the scene.
LOSER IN A SUIT: Hi, this is Rob Harasser, coming to you live from the Podunk Police Headquarters. This is Detective A. Buser Skeptic. Detective Skeptic, I understand you got a call this morning before the bombing?
WIFE-BEATER IN A MUSTACHE: Yeah, someone called me this morning. It was hard to hear them, but they said a lot of people would die in the mall today. I asked who was calling and they hung up.
LOSER: Did they say they were going to bomb it?
WIFE-BEATER: Yeah, they did say something about "a bomb", but I couldn't hear them clearly.
LOSER: Did you trace the line?
WIFE-BEATER: I did. You know, people think that if they hang up fast enough, we can't trace calls, but that's not true anymore. Even though they called the non-emergency number, I knew where they were calling from in ten minutes. It was a payphone outside the mall. Did you know there are still payphones outside the mall?
LOSER: Why didn't you warn people?
WIFE-BEATER (looking sad): I thought it was some kid playing a joke.
PANCAKE-THICK MAKEUP FACE: Well, there you have it, folks. The police knew, and they didn't tell us.