Probably because everything is happening quickly. My guess is that, yes, you can buy 4 tickets because pods are either 2 or 4 tickets. And your seniority determines the order in which those pods are offered.
Which begs the real question: how many pods are there? If everyone buys 4 tickets, there can only be 1,550 pods. But if everyone buys 2 then you need 3,100.