Clutter: In some markets or areas of markets there are so many billboards that individual messages may be swallowed up by the clutter; potential for new venues is virtually unlimited (elevators, bathrooms, etc.)
Limited programmatic advertising buys, which makes DOOH less scalable channel compared to more established digital channels.
(Source: Forrester, Weigh The Pros And Cons Of 11 Emerging Marketing Channels, 2020)