Well, the police have to take anything like this seriously, even if they don’t think that it’s likely to be anything that’s actually a real threat. If they don’t check it and it is a bomb, then they get accused of incompetence. If they don’t check it and it isn’t a bomb, people complain that it could have been one and that they didn’t do their job. If they do check it and it turns out to be nothing, they get accused of wasting tax money and panicking. And if they check it and it is a bomb, then they get to have the joy and fun of trying to figure out what to do with it. There’s more than one reason I decided to turn down a job in bomb disposal. . .
Oh, and as to the question about whether or not terrorists would use something bright and flashy and visible to put a bomb in: yes, they would.