This phenomenon is very common. In my opinion, this is the best way to check out college students' dinners. Because for college students, many people have no financial resources, and if they have financial resources, they also get them through their own part-time jobs. Therefore, students can control less money, but it is not easy to refuse some group dinners. So in order to save everyone's money, the cost of each party is shared equally by the participants, because taking their own money can make the relationship between students stronger, because there is no money exchange.
When I was in college, all our parties were split equally. Because not everyone has money, and not everyone wants to suffer, but there are many parties in universities, including dormitories, clubs and classes. As we are all students, the monthly living expenses are limited, so it is most appropriate to take our share of the money. I still remember when I was a freshman, I joined a school club. On the first day after the recruitment of the club was completed, my senior schoolmate invited some freshmen of our newly-built club to dinner. At that time, I was still wondering which senior invited us to dinner, but after dinner, we were told in the group that everyone who went to dinner had to transfer money to a senior.
So for college students, they need to socialize, but they are not enough, so the cost of each meal is shared equally.