What made Walter Cronkite "the most trusted man in America"? Why was this title bestowed on him, rather than his CBS predecessor Douglas Edwards, or any NBC and ABC contemporaries?
Also, why haven't any anchorman since Cronkite (e.g. Dan Rather, Tom Brokaw, Ted Koppel) been able to reach the same level of fame?
Some of the assumptions I made in my questions may be incorrect. Apologies if they are.
He was a nationally syndicated nightly news Anchor for one of the biggest (at the time) news agencies, and had very little competition. The reason he was so trusted is because his reporting was very reliable, especially during major US events like the assassination of JFK, Watergate, and the Cuban Missile Crises. He had a calming baritone speaking voice and spoke at 124 words per minute to make sure everyone could understand him.
A lot of things happened under his Tenure at CBS. One of which is he was the very first anchor of Americas first, half hour, nightly news segment. Most segments back then were 15 minutes, and CBS funded their news teams better than their competitors.
You also have to understand that Cronkite was the epitome of a "news man". He started in the news officially in 1935, but rose in stature during WWII. He become one of the best wire reporters during WWII. He was one of 8 journalists who was selected to fly bombing raids over Germany in a B-17 and even fired a machine gun at a German fighter. He made a glider landing with the 101st airborne during Operation Market-Garden, he also covered the battle of the bulge and the Nuremburg trials.
Combine all of that, with the fact that cable TV wasn't what it is today, and there were no 24 hour cable news networks, made him a staple in a lot of households. He also crossed over in to "popular culture" because CBS allowed shows to poke fun at him, like Archie Bunker calling him "pinko cronkite". When things took a turn, he was always there, providing accurate and reliable reporting of the news and events, and always signing off with "And that's the way it is".
Anecdotally, my parents and grand parents often talked about him, and were upset when he retired.
As to your other question, I would say Tom Brokaw has reached the level of fame that Cronkite did. Specifically because by time he retired, he was considered both in opinion polls and Nielson ratings to be the most popular news Anchor, and NBC Nightly News with Tom Brokaw was #1 from 1996 until he retired in 2004.