There are of course, places where it would be suicidal, tho not illegal, to ride on a shoulderless road. High traffic, or even low traffic with lots of semi's. Got sort of trapped in that situation one time.

We do owe it to ourselves to actively avoid such. For our own safety as well as the safety of motorist. Trying to avoid a cyclist could easily lead to a major accident, not to mention road rage. Fortunantly, where I live, sholderless two lane highways are nearly always low traffic.