Lesson learned...
 

Tried to register for an auction ending tonight with some yummy '63 & '75 TBB cards.
Unfortunately, I just found out that they don't accept registrations on the last day of the auction because they need to check references. Is this common practice for online sport memorabilia auctions?
I've bought from a lot of auction houses and just never heard of this before... figured a good credit card would do. Wishing I had registered earlier... had myself convinced that I was gonna upgrade some rookie cards tonight.

Any AH I've signed up for there was always a delay in acceptance until verification/proof of who I said I was.
Definitely could see that happening, especially on the last day of an auction, and especially if it were a bigger well known AH.

Same, gotta register. Got to wait for approval. Usually only takes a day or two, but as said, staff is likely getting busiest right before an event starts.

Thinking over it, you may be right that it is sort of unique to sports stuff. Maybe it's something about the theme/material or clientele that leads to more bad bidding than with antiques, artwork, or other fields...?

It probably also depends on how big the house is, what quality of stuff they put out, and/or their own sense of history of being burned by non-payment before (and how negatively or not that hurts their particular business model)---if it's the sort that runs high-pop, low $ items on a weekly basis, then re-running an unpaid item in short order is no problem. But the higher end sports houses may only run 3 or so main events per year, so having to re-run something later is more of an issue for their consignor who was expecting to be paid for a sale.

Once you're in though, and especially after having at least one completed invoice with the AH, you don't ever need to re-apply or be re-confirmed prior to future events. (at least that's never been my experience.)