Did you know: JCDecaux and Clear Channel are advertising companies, not infrastructure companies.
The reason you see them everywhere is because they have contracts with many municipalities; they pay for and maintain city infrastructure (bus stops, trash bins, benches, etc.) and in exchange they get exclusive advertising rights in many locations. They operate throughout Europe, and probably elsewhere.
These contracts typically come with steep cancellation fines, and are a major reason why political efforts to ban advertising in public spaces often goes nowhere; if the local government were to go through with that, they would immediately have a large cancellation fine and infrastructure bill to pay.
Often, (part of) these contracts are publicly available; consult the public infrastructure agreements and documents for your local government, and do a FOIA or equivalent request if necessary. This should tell you exactly how they are keeping your local government under their thumb.
@joepie91 now I think of it, JCDecaux is basically Google for public transit.
@joepie91 @eloy While I don’t disagree that there’s always room for less advertisement, the physical public space has cleaned up significantly compared to the (late) Victorian/Fin de Siècle era. Buildings in larger cities where a lot of people gathered were absolutely covered in ads in those days.