> Since the 1980s, we have been consistently taxing less.
Assuming "we" means the United States, this isn't really true. Tax revenue as a percentage of GDP has been remarkably stable, not just since the 1980s, but since the end of World War II [1].
The long-term average since 1945 is 16.85%, the average in the 1970s (i.e. the decade before the 80s) was 16.76%, and the average in the 2020s is 16.96%.