Why does the US keep introducing dollar coins even though nobody seems to use them?
It does seem pointless at first glance. The U.S. Mint introduced the Susan B. Anthony dollar coin in 1979. It never caught on. It introduced the Sacajawea dollar in 2000. It, too, is rarely used for day-to-day transactions. The dollar bill remains far more popular. Beginning in 2007, dollar coins will be released with the images of past U.S. presidents. Why, you ask, do they keep trying?
Because it would save the government a lot of money if dollar coins were to catch on. A dollar bill costs about 5.7 cents to print, and lasts about 22 months on average. A dollar coin costs about 10 cents to mint, and lasts about 30 years. A dollar coin is much, much more cost-effective. The only problem is that people prefer bills.
You may be interested in reading more about the Presidential $1 Coin Act