There are a few reasons why copyright terms aren't shortened:
* International treaties make it difficult without buy-in from everyone, or at least the most important countries. The USA is probably the only country that could afford to unilaterally make such a change.
* Politicians are largely beholden to big companies now.
* The average person is distracted with other societal woes, and politicians and companies work hard to keep it that way.
* Some people have been convinced that excessive copyright is a moral good through propaganda.
I’m not sure where I stand on this, but is it possible that some people have been convinced that copyright is a moral evil by propaganda? I pause when I hear this line of argument, “I’m a free thinker and I have objective truth. Others are weak minded victims of propaganda.”
Of course. There's all kinds of propaganda (and depending on where you stand, some propaganda is good and other propaganda is bad), and not one person is immune. But for the sake of this discussion, there are some extra factors to consider:
* Those promoting copyright expansion or the status quo have significant amounts of money; those criticizing it mostly do not (counting groups with real principles, anyway)
* It is suspicious for people who have no personal interest in extended copyright to excessively favor it.
* International treaties make it difficult without buy-in from everyone, or at least the most important countries. The USA is probably the only country that could afford to unilaterally make such a change.
* Politicians are largely beholden to big companies now.
* The average person is distracted with other societal woes, and politicians and companies work hard to keep it that way.
* Some people have been convinced that excessive copyright is a moral good through propaganda.