Not sure if I should carry coins for public transport in Benin or if card payments are common. Advice?
My experience was that public transport in Benin is a cash-only business. I tried to use a card with a driver once, and he looked at me like I was crazy. It's not a culture where digital payments have taken over for transportation. I always made sure to have plenty of local currency on me, and I would exchange Euros or US Dollars at an official bureau de change. This is the only way to get around reliably.
It's a very simple answer: you need cash. There's no card or payment app system for public transport in Benin. The public transport network, from bush taxis to motorbikes, is all based on cash transactions. So, before you get on a vehicle, make sure you have enough CFA francs (XOF) on you. You can get cash from a local bank ATM in Cotonou, but don't count on being able to use a card for a ride.
Don't even think about using a card for public transport in Benin. The system is entirely cash-based. I took a few bush taxis and mini-buses from Cotonou to other cities, and every single driver expected cash payment. No one has a card reader or even a mobile payment system set up for this. My advice is to have a good supply of CFA francs on you, as it's the only way to get around reliably.
You should absolutely carry cash for public transport in Benin. The public buses and shared taxis, which are the main forms of transport, are a strictly cash-based system. You won't find any card machines or digital payment options. The currency is the West African CFA franc (XOF), and it's best to have plenty of small notes for your fares. You can get cash from a bank ATM like the one at Société Générale or use an international travel card like Wise to get local currency.