The problem is hackers sign up and authorize a seller's account too so eBay can't just trust that.
There is a difference between someone who has been an Auctiva user for a year, and someone who just signed up today and then proceeded to put up 35 pairs of sunglasses at suspicious prices with 1 day listings.
eBay is more closely checking newly registered customers accounts to make sure they are legitimate from what we can tell. They don't tell us what they do, when, why, or anything else. It takes from a few minutes to a few hours and then after that you should be able to use our service without delay.