I'd say the auctioneers are making their money from a contract with the receivers. Ebay introduces complications not usual for such a deal. There would be a need to "close the books" on it quickly. The receivers themselves would be under time pressure to do the same on behalf of the creditors.
There could be time pressure to clear out a building but in this case it seems they have enough time to organise an auction. Also sensible creditors make sure they get the most of their money back and not a quick buck made by selling off everything way too cheap. BTW 'that is the way of things' doesn't sound like a good breading ground for doing business in an innovative new and more profitable way.
eBay just plain isn't more profitable for auction houses. I know auction houses that looked into eBay to try to increase revenue and quite simply it doesn't. eBay has been around long enough that the major auction houses have looked into it and decided it is not worth the hassle.
According to an aquiantance who is an auctioneer:
1) They take a HUGE cut of the profits, between PayPal, eBay fees, etc. You will notice, there is a buyers premium paid by the buyer, directly to the auction house. On eBay those fees are paid by the seller to eBay. These fees can add up to a significant portion of the final price.
2) There is DRAMATICALLY more overhead for eBay selling. Even in listing, you need to hire people to handle the detailed ads (otherwise you will get a dramatically lower price than at auction). These hires eat into the profit.
3) You need to handle shipping, which means a shipping department (which means a multitude of employees). They have to handle packaging, customs forms, etc. This is a VERY expensive overhead cost, which eats into the profit even more (if not turns it into a solid loss). Traditional auction houses require the buyer to arrange for a shipping company to handle this otherwise they pick it up.
4) You have to handle returns, damaged and lost goods. This leaves the books open way longer than necessary which costs them a LOT of money.
Quite simply, from the auciton houses perspective, eBay is not some bold new frontier, it is just a huge money sink. When eBay first came out, my acquaintance knew many auction houses (including his own) that dabbled in it and without fail they all said they lost money on the venture. The slight increase in prices and exposure doesn't nearly offset the huge increases in cost from doing business on eBay.
EDIT: Clarified somethings and removed some redundancies.