Do standby flight attendants get paid while waiting at the airport?

Not complaining, just genuinely curious.

I saw someone mention that AA keeps backup flight attendants at certain airports in case someone can’t make their assigned flight. That makes total sense operationally.

But how does that work pay wise? I always thought FAs were only paid once the aircraft door closes. So if they’re sitting around on standby at the airport waiting to maybe be used, are they getting paid for that time?

Would love to hear from anyone who knows how it actually works. 😊