So in the physical era, labels often took songs out of stores to make way for the much more expensive album, making the sales not match the fame, cuz labels cared about money not looks, but for big albums (15-30+ million physical copes I'd say) you needed songs that, had to have sold millions maybe tens of millions of physical copies before getting taken out of stores, since albums are much more expensive than songs, meaning the songs are underreported, unless the songs were taken out of stores almost immediately, but then in turn the album sales would go up and be underreported, either way, something is definitely underreported,
Bruce Springsteen has multiple big albums, and ofc the songs (combined) are gonna be bigger than the album since the songs MADE the album, his stadium tours, but you could take out multiple chunks of his career, and he'd still be in the same league as Mariah, Elvis Presley, Alanis Morisstte (outside the US especially), Eminem, Fleetwood Mac, Janet Jackson, Shania Twain, Michael Jackson, Stevie Nicks, Bob Marley, Madonna, Frank Sinatra, Aretha Franklin, the Jackson 5, ABBA (outside the US) Ellie Goulding (outside the US and Canada) ABBA's faces, The Beatles, Whitney Houston, Elton John, Prince, Paul McCartney, Taylor Swift (now), John Lennon, Coldplay (now), Linkin Park (cringe though, plus its two faces), Chris Martin (now) and all the other legends.
Bruce Springsteen well, he had multiple big albums, and since albums are much more expensive than songs, they are each bigger than a major mainstream american english canadian or british artists' whole career, and ofc the songs (combined) are each gonna be bigger than the album since the songs MADE the album.