Voters are playing it safe. That's why the two candidates with the most name recognition going into the primary were the top two candidates. That's why the two VP possibilities who have the most name recognition now poll the best.
Media coverage during the primary followed the polling. It wasn't some grand conspiracy. Warren and Harris got spikes in media coverage after they spiked in the polls. Same for Beto and Pete.
The Economist/YouGov poll is interesting. This is what NBC News says about it:
An
Economist YouGov poll this month found that Harris led Warren by two points among black Democrats asked for their vice presidential preference, inside the margin of error.
That's not what the poll actually says. Sure, Kamala got 21% among Black Democrats (N=106) and Warren got 19%. But "Not sure" got 28%. Biden voters overall were 28% "Not sure." Here's another way to look at the polling among Biden voters:
30% Someone besides Harris or Warren (Abrams 9%)
28% Not sure
24% Kamala Harris
18% Elizabeth Warren
Here is the polling among Black voters:
32% Someone besides Harris or Warren (Abrams 14%)
28% Not sure
21% Kamala Harris
19% Elizabeth Warren
Then look closer. Here is the percentage among Black voters/Biden voters/Independents (there is some overlap) who list "Don't know" as the favorability for each potential nominee.
Abrams 39/35/50
Baldwin 62/60/68
Bottoms 48/58/65
Demings 57/62/70
Grisham 69/72/70
Harris 27/16/36
Rice 53/46/53
Warren 23/10/30
Whitmer 57/52/59
Warren, Harris, and Abrams are the only ones who we can even say are known among people who might support the ticket. And even then Warren and Harris don't have particularly strong support. "The media" are trying to make it seem like a two woman race when the reality is Black voters and Biden supporters in general don't really have a preference. Most likely they'll just roll with whoever is picked.