Event-based campaigns can are unique in that they can successfully use either the business-led or customer-led campaign, or even a combination of both!
Maybe your business is hosting an event where a professional photographer or trained staff member will be in attendance to take photos, but you also like the idea of having guests showcase their experience. It is 100% possible to combine both types of campaigns to accomplish that!
Also, because events tend to have a shorter timeframe than a longer campaign that might be employed at a restaurant, for example, there may be more excitement over customers taking and sharing their own photos because they are likely to be taking selfies of themselves during the event anyway!