Limiting it to this sort of context (deliberately excluding web stuff, where there may be more argument): I don't believe there is anything nice the ads are paying for.

Certainly, for information systems in public transit that would be hard to argue for. However, I took chgs' remark to be more general.

Maine has no billboards for several decades now, and miraculously our state has not suffered existence failure, and we still build and sell a bunch of nice stuff.

Never believe a marketer telling you that you NEED marketing. Life will go on even with very limited marketing. You and your neighbors do not need it. Capitalism does not fall apart if it gets more expensive to force someone to learn about your product when they do not want to.

On the scale of the public, the public should just not sell ad space. The public finance the conaumer prices in the end anyway.