Although "The Road Not Taken" by Robert Frost was written during the same time period as the modernist poems of Pound and Eliot, Frost himself was not a modernist, being more closely allied to the distinctly anti-modernist Georgian poets. In fact, one could even argue that the well-travelled poetic road Frost chose not to take was that of modernism.
Let us examine the second stanza:
Then took the other, as just as fair,
And having perhaps the better claim,
Because it was grassy and wanted wear;
Though as for that the passing there
Had worn them really about the same,
The poem is written in relatively regular iambic tetrameter lines with frequent anapaestic substitutions, in simple, almost Wordsworthian language. It uses a regular ABAAB rhyme scheme, with traditional full strong rhymes rather than half-rhymes. The lines are mainly end-stopped. There are no obscure allusions, elliptical references, invocations of major philosophical or artistic theories, portrayals of the fragmentation of the modern world and sensibility. The narrator is reliable, etc.
It's important to realize that not everyone born in the same period has the same beliefs or artistic sensibilities. Although the modernists were a very important group of early twentieth-century writers and artists, not all writers alive in the period were modernists. Many, like Frost, the southern Fugitive poets, and the British Georgians disliked international modernism and focused more on developing traditional verse rooted in a regional sensibility.