> The copyright goalposts have moved so far past where they were originally, the people who work very hard can be dead for decades and their works still in copyright, and by the time they are dead for 70 years
Note that copyright lasting 50 years after the author's death was already in Berne Convention from 1886. Some (but not all) of these extensions in US were just adaptation of older weaker US copyright to international conventions.
Those "international conventions" were still established by lobbying from the US copyright industry. International treaties are a great backdoor for laws that a government wants to pass but which are unpopular with the population.
Note that copyright lasting 50 years after the author's death was already in Berne Convention from 1886. Some (but not all) of these extensions in US were just adaptation of older weaker US copyright to international conventions.