It’s cheaper than a caterer. Usually, most caterers offer “party packs”, wherein they serve take away trays of their usual fare that’s good for 10 to 30 people. What makes it cheaper compared to getting a buffet service is that you’re paying for the bare minimum of the caterer’s service, which is the food. It excludes everything else, like the wait staff, catering equipment, perhaps even the tables and chairs that come with the catering service.
It’s handy to bring anywhere you go. For events held in hard to reach areas, say a team building in a secluded beach, bringing a caterer along might be tricky. Even finding a restaurant nearby will be a hassle! Bringing packed meals will be your best and most efficient bet.
Distribution can be easier. For some caterers or food providers, they can do packed lunches made for per person, to take out the hassle of bringing extra plates and utensils, and having your guests help themselves to the big party packs. It also ensures that no one will go hungry too, since people have a reserved lunch waiting for them.