Paul Carey has called on the Scottish Government to force companies like First to be accountable for public money.
The Labour councillor has made the call after saying he has spent months trying to get answers from First Glasgow on what happens to excess fares it collects.
But the Scottish Government has already dropped proposals to expand Freedom Of Information laws to a series of private or semi-private entities, including Glasgow Housing Association and firms that run jails.
Mr Carey said: "Hundreds of buses on the roads covering Strathclyde and beyond are operated by First Bus.
"First Bus refused to advise me what happens to the excess fares based on company confidentiality.
"I have now written to Scottish Transport Minister Keith Brown to request the Scottish Government's views on First Bus coming under the Freedom Of Information Act."
An excess fare is the extra cash passengers put into the money box because they do not have the exact fare and drivers do not give out change.
First, which grew from Aberdeen's municipal bus company into a multi-national giant, is a private company and currently under no obligation to respond to requests for information.
But it does get public money and Mr Carey said SPT – the regional transport agency for west Scotland – gave First more than £1million a year.
He said: The Freedom Of Information Act should cover First Bus and, in my opinion, the company should confirm what happens to excess fares.
"I believe these excess fares should be used for bus routes that are no longer making a profit.
"I await the Scottish Government's response on this."
First Glasgow was not impressed with Mr Carey's suggestion. Managing director Ronnie Park said: "As a private company we are not bound by the Freedom Of Information Act."
The Glasgow division of the firm has been in the wars in recent weeks after announcing the biggest shake-up of its city network in more than a decade.
The firm is concentrating more on major arterial routes and cutting back on more peripheral services, including those linking city hospitals.
In unusually strongly worded criticism, SPT accused First of running a "sham consultation" on the changes.
But First is not obliged to run any kind of consultation about its network and has always insisted its plans were "not set in stone". It is understood to be tweaking proposed changes.