I would want to answer this excellent question by considering the way in which Frost uses symbolism so that he can simultaneously talk about the beauty of nature and his experience of living and owning a farm in New England, whilst also suggesting deep and profound truths about what it means to be human. Consider, for example, "After Apple-Picking," in which Frost, through the example of picking apples during the apple harvest, is able to suggest much deeper truths about the human condition and work. Consider the way that apples symbolically represent opportunities and aims in life, which, when achieved, lose something of the lustre:
For I have had too much
Of apple-picking: I am overtired
Of the great harvest I myself desired.
Frost thus communicates the way that so often what we desire and work so hard to gain actually becomes something that we tire of later on in life and regret.
In the same way, "Stopping by Woods on a Snowy Evening" is a poem that talks about the desire for rest and a peaceful death whilst balancing that desire alongside the need to fulfil the various responsibilities that we have. Consider how the final stanza of this poem communicates this:
The woods are lovely, dark, and deep,
But I have promises to keep,
And miles to go before I sleep,
And miles to go before I sleep.
Here we can see how the woods are used as a symbol of eternal rest, which sounds so attractive to the speaker. However, the "promises" that he has "to keep" prevent him from resting and force him to persevere with his life.
We can therefore see the way in which symbolism is the prime vehicle that is used by Frost to use rural life to comment upon the human condition.