That always made sense to me, Shepard is a military hero, not a pop star or famous actor. Regardless of what he does, he will never be as recognisable to the masses as a Beyonce or Brad Pitt, especially in a galaxy supposedly made up of trillions of individuals who don't all follow the latest news closely. Blasto is probably much, much more recognised than Shepard.
Indeed. Granted, post-war, that's very likely to change.
Shepard's fame isn't the pop-star/rock-star/entertainment celebrity. He's more of the icon of humanity and legendary figure. He's the type of guy who's going to have statues built in his honor. He's like a person who's become a national treasure.
Like Sir Edmund Hillary or Neil Armstrong or Mahatma Gandhi or Nelson Mandela. They weren't 'in-the-news' famous, but they were hailed as living legends of their time, the pride of their respective countries, national heroes that everyone knew. And Shepard's legacy will be like that of someone like Einstein or Lincoln or JFK (albeit on a much, much, much higher level). Hell, I daresay that post-war, Shepard's status among humanity at least will be on par with Christ or other significant religious figures (sans the religious nature since my Shepard is an atheist). He will basically become a messianic figure.