I don't know the ins and out but i know the price snapchat asks is 750,000 a day for a takeover, putting that into consideration you can make an educated guess that being in the filters isn't a 'who ever wants it' scenario.
I didn't say people are fighting over it but snapchat has a huge audience, im not sure how the filter works but if any brand got in there for free snapchat wouldn't be asking 750,000 for a takeover. Maybe if you had an understanding of how advertising, marketing or brand placement works you coulda figured that out.