Confused American here. Fans at our professional sports all purchase tickets the same way and inter-mingle in the stands, and yes there is sometimes a fight or two but mostly just some yelling and joking. Our college teams do reserve special blocks of tickets for opposing colleges, but I have never heard of a college being blocked (correct me if I am wrong). Why is this so prevalent in Europe, you Europeans here? Couldn’t everyone mingle or would chaos truly ensue?