1979 was Jimmy Carter, a Democrat. Reagan did not start until 1980, and while he is famous for breaking the backs of unions, thus crippling their ability to fight back against this trend, he did not actually start it.

Before Carter was Ford and Nixon, both Republicans. Ford pardoned Nixon’s crimes, supposedly to help “heal the nation”.

According to Robert Reich’s “Inequality for All” (free link) - he was the Secretary of Labor under Clinton and previously served under both the Carter and Ford administration so he was very much attuned to what was going on - this trend started due to the rise of corporations, which have super-rights that humans do not have. e.g., taxes on stock dividends were capped at like 13% while payroll taxes can go up to >35%, and while if a human commits a crime they would go to jail, but not so with a corporation. It’s a great racket scheme for the rich to cover themselves in a legal fiction so as to avoid pretty much any responsibility for their actions. Hence why we see so many corporations acting so very boldly to destroy the planet - after all, why not? What’s the worst that could happen to them in return?