Because it's no more eligible to run than any other process. If it kept cutting in front, you could end up with thread starvation, where nothing except 56 gets to run or where 56 got way more time on the processor than anyone else.

Say your supermarket queue had 1 person who needed a price check, one who asked for cigs to be fetched for him (here they have to be fetched by someone), one has a credit card which required authorisation and one forgot an item. They've all now got what they needed and are just waiting for the cashier to be free. Which is going to go first?