This is a guess based on observation, not an intimate awareness of the MagicBand touchpoints. We have 45th anniversary Magic Kingdom MagicBands. My Haunted Mansion band should glow green and purple and make the sound of the doorbell. My Mom has Dumbo the Flying Elephant and it should be a rainbow and play Casey Jr's Comin' Down the Track. Whenever the lines at the gate or attractions have been long, there is no effect. I have assumed that people wait to see the glow and hear the sound and, when necessary, the effects are turned off to expedite the lines.
I have the Dumbo band but it is always so noisy I have never been able to figure out what the song is that plays when scanning at FP+ tapstiles. so thank you for that! The cast members at the Flying Carpets were excited to see the rainbow and hear the music when I checked in there
Mine only turned purple the day we went to EPCOT which happened to be the day we checked into Poly on points. I got stupidly excited and put both hands up and yelled "YES! IT WORKED!" and looked over to see the crabbiest old lady cast member I've ever seen. She gave ZERO rips about my purple light and didn't even make eye contact. I turned around and started dying laughing to my husband because it was so embarrassing. He was like" See! Nobody cares that your DVC. "(I get teases mercilessly in my family because of my DVC love).
Whatever, he's just jealous he didn't get a purple light.