> Pakistani weddings i think would not be street vendor but catering service
Largely depends on how rich you are. Middle-class and above tend to hire a Wedding Marquee, which basically means a hall and catering service along with decoration shenanigans. So, largely, yeah, food is catered.
However, poorer folks will not be able to afford such a thing. Therefore, food is going to be cooked the traditional way. Now, since weddings tend to be fairly big, huge events with over 300/400 people at the minimum. This means that you need big pots and pans to cook lots of food. Kitchen ovens are often smaller sized and difficult to cook on, so specially made massive pots for cooking are used on wood fire outside where cooking is done.
Although, I will say, I've eaten at a fair few weddings, and actually aided the cooking effort in two or three, none would ever allow any bird or any other sort of animal near it, and hygiene was as high as it could be. Food ingredients are kept covered with some sort of netting/clean cloths while pots and pans are always covered with a lid. More so, meat and other perishables that might be affected by the heat are basically brought directly out of fridge and into pot.
Crows and other birds getting some food is only when leftovers are thrown to the side somewhere, so this, hopefully, isn't a common thing.