Why is American money green?

In 2003, during time Green Day spent time in the studio, a New Wave band known as The Network appeared on the scene. Three of the five members of the band are allegedly the three members of Green Day. The frontman, known only as "Fink", is believed to be Billie Joe Armstrong. Armstrong has referred to himself as Wilhelm Fink in the past, and a Pinhead Gunpowder fansite bio of Billie Joe Armstrong confirms Fink's identity. Armstrong's voice is also unmistakable on The Network's albums. The Network's bass player, known as "Van Gough," is supposedly Mike Dirnt; and The Network's drummer, "The Snoo," is thought to be Tré Cool. John Roecker, director of Live Freaky Die Freaky, starring Green Day and other East Bay punk alumni, and Green Day's DVD Documentary Heart Like a Hand Grenade, has spoken of various projects recorded at Studio 880, including a New Wave album and a Christmas album, during the sessions of their latest album. Studio 880 is the credited studio in The Network's Money Money 2020 album and Green Day's American Idiot. No official connection has been made between the two bands, and both bands have defended, sometimes aggressively (in a probably staged press conference where some members from both bands engaged in a heated argument that broke into a minor conflict), the lack of connection between the two. Green Day's management has always declined to comment on the ongoing situation between Green Day and The Network. On October 6, The Network agreed to support Green Day with Jimmy Eat World on the American Idiot tour. Sources close to Green Day have been quoted as commenting, "That's a really bad idea," and, "Can we just make them go away?"