I understand that the city buses in Reykjavik do not accept cash or credit cards. Because I can’t walk well or far I will need to use the bus system. How do you pay?
Strætó in the capital area is in the Klapp ticketing system.
You can pay with:
Klapp ten
Refillable Klapp card
The app Klappið in your phone
Cash – Drivers don´t give change in the capital area
https://www.straeto.is/en/user-information/faq
Looks like you can pay in cash but need exact change,( or end up over paying)