"Pretty sure it's also an excuse to keep the bomb squad and evacuation procedures in practice."

Definitely not in this eastern part of germany where I live. Every major construction needs to check for bombs, but it also happens randomly that a excavator finds a bomb.

There were just a looot of bombs dropped. (And they don't always move it, often it is too rusty also to defuse and then controlled explosion if the surroundings allow it (they use lots of water bags on top, witnessed it once))