This is rather annoying and should be very basic and simple. I came from Windows Phone, and despite all the negativity surrounding it, it has features that other phones do not. For example, holding down on an unknown number that just called, and blocking it right from the menu.
I've seen other Androids do this but they're Samsung. I see no easy way to do this and online searches return nothing.
I also dislike Droid for its inability to read texts over the car's Bluetooth but that's another issue for another feed...