Plenty of settlement systems permit arbitrary precisions of dollars. It’s just useless for day to day purposes for most people, so a consumer version never took off.
As stated by Wikipedia (https://en.wikipedia.org/wiki/Micropayment): "One problem that has prevented the emergence of micropayment systems is a need to keep costs for individual transactions low,[2] which is impractical when transacting such small sums[3] even if the transaction fee is just a few cents."
0 fee solves this issue. I don't see any traditional system that does the same or better than Nano to be honest.
