Well, 81 minutes vs. 20 seconds does seem pretty extreme. Donald Trump is a human headline, but is he really that much more newsworthy than Sanders? No.
But, generally speaking, Trump-Sanders is a bad comparison, even though -- as Republican strategist Tony Fratto pointed out on Twitter -- the two candidates register similar levels of support in national polls. (In fact, Sanders is polling slightly higher than Trump at the moment, according to RealClearPolitics averages.)
Here's the thing: Winning matters. While Sanders trails Hillary Clinton in the race for the Democratic presidential nomination by 23 points, Trump leads the Republican contest by almost 15. Trump looks like a real contender -- maybe even the favorite. Sanders, still, looks like a long shot.
The same principle extends beyond politics. If you follow the NFL, think about how much more coverage ESPN has devoted this season to the New York Giants, Philadelphia Eagles and Washington Redskins than, say, the Oakland Raiders and Chicago Bears. All five teams have 5-7 records. The difference? The Giants, Eagles and Redskins are in a virtual tie atop their division, the NFC East, meaning any one of them could win and make the playoffs. The Raiders and Bears, meanwhile, are out of the running because other teams in their divisions are having much better seasons.
Simply put: Polls and records are important -- relative to the polls and records of your competition.
Sanders probably deserves more attention than he has been getting, and it's easy to understand his frustration. But, realistically, he isn't going to garner the same level of coverage as Trump. And he shouldn't.