At least in Puget Sound, every transit operator (except for Community Transit) makes their real-time bus arrival data publicly available for free via Sound Transit's Open Transit Data service, OneBusAway: https://www.soundtransit.org/Open-Transit-Data
(OneBusAway is the name of the app that shows information to end users and the name of the API service that developers can query.)
I know that this service is widely available and free because I've had an API key for years and have (accidentally) pummeled the service with requests and have heard nary a peep from Sound Transit asking me for money.
Good for you and your city. My hometown apparently made an exclusive deal with a startup, which I hear is why we still can't see bus schedules on Google Maps.
(OneBusAway is the name of the app that shows information to end users and the name of the API service that developers can query.)
I know that this service is widely available and free because I've had an API key for years and have (accidentally) pummeled the service with requests and have heard nary a peep from Sound Transit asking me for money.