Check out this thread I had featured here on CoinTalk concerning a great book on Dollar Coins https://www.cointalk.com/threads/red-book-modern-us-dollar-coins-book-review.308422/
There is no need for a modern dollar coin. The vending machine industry took care of that just like the circulating half dollar.
The vending machines at my work have card readers. $0.75 for a canned drink with cash, coins or bills. $0.85 for the same if you swipe your card.
Those coins were made of 90% silver and were commemoratives that were not intened for circulation. 1990 2013
It would have remained the same size if it had been used in circulation, but like its silver dollar ancestors, people thought that it weighed too much and was too much trouble to carry.
