U2 and Green Day are like identical twins.
At first blush, the statement is obviously false. Their beginnings are over a decade apart and they don't sound all that much like each other. The idea started when I began to realize they occupy very similar spaces in musical history; serving the identical purposes in their respective times. You see, they both ended up as harbingers announcing the end of what had previously been periods of chaotic creativity and musical expansion.
When U2 came on the scene, post-punk was in full swing. I've put forward my theories and thoughts about that era plenty enough, so I'll try and keep it brief here. The punk explosion inspired hundreds of kids across Britain to rush out and start their own bands, but by the time those kids could string 3 chords together, punk imploded. It didn't just stumble or stop, it ended ignobly. The Sex Pistols signed to a major label (gasp!) that ultimately stifled them, then they flatlined in an excess of drugs, ids and egos. For all their DIY, fuck-the-man bluster, their collapse could have been any of the 70s dinosaur acts they sought to make extinct. Those kids they inspired responded by not repeating their sound or path but tearing everything apart. Post punk made some of the most unruly, experimental rock up to that point and it was often recorded in their own studios, on their own terms, and released on their own, new independent labels.
From a major label's perspective it must have seemed like actual anarchy. They had no idea how the taste of kids got out ahead of them. Instead of setting trends, they were now in a place of scrambling to keep up. Enter: U2. Listening to their debut, Boy, Bono & Co. had many hallmarks of their era: scratchy guitars, lugubrious bass, relentlessly repetitive rhythms, a singer with an off-kilter voice... but there was something about them that seemed ready for the big leagues. It's almost impossible to imagine a band like U2 ever playing to a crowd of 15 in a small club. They were designed for the stadium. It was huge: go big or go home.
This is exactly what the music industry needed: a mold; a template for spinning post-punk into Grammy-winning gold records. They would no longer take a risks on unruly, experimental acts with sounds unheard before on the face of music. All that was needed was more of this, and this was U2.
Flash forward one decade and Nirvana upends the scene. Nirvana did not come from out of nowhere. There are direct chains of precedence and influence--a context in which they make perfect sense-- but the landscape of mainstream pop radio onto which they exploded was filled with the likes of Madonna's Vogue and other things I shudder to think about like C&C Music Factory. Their runaway success, seemed to catch major labels resting on their laurels, and led to a subsequent feeding frenzy. College radio bands that had been kicking around the underground for years got snatched up into big deals, whether it made sense or not.
They had the right, now sound, but tweaked it perfectly. The guitars still burned but they no longer snaked or tangled--they moved in giant, simple, dayglo patterns. It was as easy to grasp as children's toy blocks. They had attitude, but it was more snotty teen than tortured soul. It was at once anthemic and meaningless.
With Green Day, the marketers of music once again had their mealticket. There would be no more ugly bands like Pixies or Replacements given air. It was to be Blink 182 and the Offspring from now on. Green Day's success was both bankable and replicable.
Having mulled over this idea for a long while, I started to see even more similarities. Green Day tried to mature into a 'message band'--something U2 embraced early on with Sunday Bloody Sunday and their odes to Martin Luther King Jr. In all cases, the message was never specific or targeted... or even that personal: it was designed for universality. Decrying war, as a concept, is about as controversial as taking a stand against cancer. I remember Green Day's American Idiot being equally popular with the "Let's Roll" hawks as "9/11 was an inside job" doves. It was full of fist-pumping good times and toothless, vague introspection.
Of course they both periodically rebel against their own maturation with diversions--getting back to their roots, as it were (whatever those might be). Around the time of 2000's All That You Can't Leave Behind, I'd taken to saying that U2 was the best U2 cover band ever. Lately, Green Day has arguably earned a similar honor.
Lastly, lest we forget: they both debuted Broadway musicals--almost simultaneously. That one's a little hard to swallow.
So yes, U2 and Green Day may not have much in common sonically, per se--at least no more than any other rock band of their time--but they do seem to occupy the same cultural space. They both serve as the lowest-common-denominator force that ended the post-punk and grunge eras (respectively). Certainly, it was bound to happen, all periods of furious creativity come to a close, but it is interesting to examine the means and instruments of those ends.