Open Data is scary and can vastly undermine the companies - most of European public transport is done by public tenders. You want to be able to provide what's required as cheaply as possible. That means as few busses and more important as few drivers as possible (labor costs are the highest). If the contract is up for grabs and your competitor can see how many busses you need at any given time for instance, that means a tremendous win. Sure it's still a bad argument, but there is some say for threatening their business.
Here in the Netherlands lots of the tenders/contracts contain provisions for providing the data to "regional or national transport planning systems", which is a very vague stipulation, and it's still hard to get data providers to provide the data.
Wouldn't open data make a bus company more popular to another one that does not release its data to the public? But here in Colone there is only one bus company, which might be the reasons why there is no public API---why put extra effort if there is no competition?
Here in the Netherlands lots of the tenders/contracts contain provisions for providing the data to "regional or national transport planning systems", which is a very vague stipulation, and it's still hard to get data providers to provide the data.
A great site for GTFS based data (maybe including your city?) is http://www.gtfs-data-exchange.com/. Use data from it and https://github.com/openplans/OpenTripPlanner/wiki/ to build a trip planner for your city in an hour.