How does that prove you've been vaccinated?
I mean, it proves you bought the band. Proves you uploaded a photo. We can see the photo, maybe that's your card, maybe it's real. Maybe you're a crazy person who's sure "The Man" is out to get them and it's all fake.
The NY system at least verified with the provider. There was a kickstarter that would get you 5 bands, color coded, for the same $20 I think. About as useful, especially the one that said "I'm infectious, stay away".
If you already have a magic band that looks like this, just wear that. You can people the vaccine is just like magic.

It kind of is, so it's truthful in that sense.