On a recent taxi ride to the airport, a Twin Cities woman noticed that the meter started near $6. After reading postings in the cab, she realized she had been charged the normal startup fee, but also an "airport use fee."

"The [$4] fee is only collectible by taxi companies that are permitted by [the Metropolitan Airports Commission], and the permit is for picking up at the airport, not for picking up anywhere else," airport spokesman Patrick Hogan said.

When the woman balked, the driver reduced the fare by "a dollar or two," and the cab company said mistakes happen.

So she contacted Whistleblower: "This little 'self-tip' should stop." Have you encountered the same problem? Comment at startribune.com/whistleblower.