I am very new to space exploration by humans (was always much more interested in astronomy) and have just begun looking at rocket launches in the 1960s because my little four year old is interested in them, and I was 4 years old when Apollo 8 launched.
There seems always to be a very clear and emphatic statement "We have cleared the tower" when this event happens in the Apollo missions and earlier ones. I am not even sure who makes this statement, but it is always very noticeable.
My question is this:
Does the point of having cleared the tower signal a procedural shift: e.g. defining measures for various staff to take in an emergency and therefore something that everyone would need to know about?
My understanding is that before clearing the tower, there was very little anyone could do but hope that the launch vehicle actually clears the tower, and after that time there may be some hope of a successful escape with the escape rockets (I'm specifically talking about Apollo here, although my recollection is that there were escape rockets even for Mercury). Or is this kind of obvious statement perhaps just for the general public as a kind of exuberant "this really is IT!"?