...sorry I could not travel both And be one traveler And both that morning equally lay In leaves no step had trodden black. Oh, I kept the first for another day!

nice that the few interpretations I find online all do speak of the common misinterpretation.

the answers site does well, and I did not know:
Frost is said to have written the poem as a sly joke on his friend Edward Thomas oh!, and to have warned audiences, "You have to be careful of that one; it's a tricky poem—very tricky."

also: Ironic as it is, this is also a poem infused with the anticipation of remorse. Its title is not "The Road Less Traveled" but "The Road Not Taken." ah right.