Quid Pro Quo, Clarice.

For some reason, This story at The Burgh Report from the P-G:

A 1,200-square-foot electronic billboard will decorate the rising Grant Street Transportation Center as part of a deal between Pittsburgh officials and Lamar Advertising to trade old, paper signs for new, illuminated ones.

Because of its size and cost, the sign would normally need zoning
board and planning commission approval, but it is proceeding with neither.

reminds me of another story from the P-G:

He [Ravenstahl] promptly seized Mr. O'Connor's focus on "redding up" the city -- and the free billboard exposure, courtesy of Lamar Advertising, that came with it. Later came another series of billboards touting the city's 311 help line, also with the mayor's name and face prominently displayed.

Lamar currently has five such billboards citywide, which cost the company a total of $265 in materials and two hours of staff time, according to Stan Geier, the company's local vice president and general manager. "It is ad space that went unsold and is not displacing any paying advertisers," he wrote in an e-mail response to questions.

The signs are consistent with the company's practice of donating surplus space "as a public service to deserving organizations," he wrote.

. . . but I can't quite put my finger on why.
.