In the case of the portion of the road running through the Waldorf area, it might well be so expensive that it might (I emphasize "might") be more cost-effective to bypass the area, which of course would prompt another round of battles both because of the people along the bypass routing opposing it and the businesses in Waldorf not wanting to be taken off the main road.
It has been discussed and studied.
The Smart Growth industry has repeatedly tried to stir up opposition to a relocated U.S. 301 in Charles County around Waldorf, but Charles County is not especially fertile ground for such activities - it is about 10 light years away from Montgomery County, Md.
Charles County is
Southern Maryland, with an emphasis on
South. If you were to wear a blindfold and not have a GPS unit, and be dropped off in the middle of that county, you might think you were in South Carolina and not Maryland from the surroundings.