Metrification was at its height in the 70s, during the Cold War where most people were resistant to any kind of change. The committee in charge of implementing the system was created by Gerald Ford (who was unpopular due to the Nixon thing) and then overseen by Jimmy Carter and Congress, neither of whom particularly supported the committee, just expected it to make things happen magically. Reagan came to office in the early 80s, and seeing the cost issues with changing the systems, nixed it. Metrification was out of vogue by then, and no current politicians want to say "let's spend money to change all the perceptions you know" to the public. Generally metric is still used by shipping and science fields, but the public still primarily learns imperial.