Why would the first road be "scary" and then the other be "just as fair"? "Fair" is a positive description.
If both roads are just as fair as each other, there isn't one scary one and one happy one, there's either two scary ones or (more likely) two happy ones.
Anyway, shouldn't it be ONE road diverged in a yellow wood? If TWO roads diverged, that would make four.
The poem is about a man who, "years and years hence", will be remembering his life, and up there near the top of his memories to tell people about is how he chose which of two almost identical paths he took when walking in a wood, once, and they were roughly the same. Does that sound like the sort of memory someone who would pick a scary road would choose to reminisce about? Does it sound like the sort of tale a habitual liar would tell? No to both. It sounds like the sort of tale a really boring person with no interesting memories would tell.
He was walking through a wood, not trying to get anywhere in particular and not caring where he went. It was probably quite pleasant, and it wasn't the hundred acre wood or the Lord of the Rings evil forest, both roads came out the other side of the wood and then he went home.