All cars have soundproofing, some a lot more than others. High end luxury cars barely let any noise in as it would annoy the people being driven around by their chauffeur.
Most roads have vehicles driving in two directions not all going in the same direction. Cyclists are banned from motorways and no sane cyclist goes on dual carriageways.
If your headphones block your hearing then you've got it turned up to loud and will be damaging your hearing. I can listen to music, podcasts etc. and still have a quiet conversation with others.