It is 90 days for most nationalities, including US and Canada. The reason the card says 30 days is they're still using up their printed supply from the 9-month period last year when they shortened the "automatic" period from 90 days to 30 days.
To look up Panama's requirements for all countries, go here:
http://migracion.gob.pa/eng/servicio.php?cont=paisvisa