Not sure if I should carry coins for public transport in Panama or if card payments are common. Advice?
I made the mistake of trying to board a MetroBus in Panama City with just cash - the driver refused and pointed me to get a Metro Card first. Later, in David, I had only $20 bills from the Banco General ATM, and the bus driver to Boquete rolled his eyes at me. He finally took it but shortchanged me. Definitely keep smaller bills, and get the Metro Card in Panama City right away.
Panama City transport was simple once I had the Metro Card. Tapping in and out of Albrook, 5 de Mayo, and Iglesia del Carmen stations felt quick and easy. I loaded the card with cash at a Banistmo kiosk and used it for buses too. For smaller towns, cash worked fine - nobody complained about $1 bills. ATMs from BAC Credomatic in El Cangrejo were reliable. Overall, smooth experience.
I stayed in Casco Viejo and used the metro daily. I bought a Metro Card for $2 at Albrook station, then loaded $5 cash at a kiosk - it worked seamlessly for both the metro and MetroBus. When I went to Boquete, though, the local buses only took cash. ATMs from Banco General in Casco Viejo gave me $20 bills, which drivers sometimes struggled to change. I usually broke them at Rey supermarket before heading out.
In Panama City, public transport relies on the MetroBus and Metro systems, which use the rechargeable Metro Card. You load it with cash at kiosks or at Metro stations. Cash is not accepted on buses directly. ATMs from Banco General, Banistmo, and BAC Credomatic are easy to find in the city. Outside Panama City, small buses (colectivos) usually only take cash, and USD bills are standard since Panama uses the dollar.