Compared to the purchasing power difference between 1800 and 2021, a dollar buys (almost) exactly as much in 2021 as it did in 2020. ("Almost" in parentheses, because at any reasonable precision, the 20/21 difference will probably round to zero.)
When they're big enough, differences of quantity become differences of quality.
Inflation was known to legislators back then so its way for legislators to lower the bar and catch more people in the future, without anyone picking up on it at the time.
Anyway fabricating evidence has been around for as long evidence has been needed to settle disputes.