One reason given is a general misconception that trustee firms handling the auction or the banks are responsible for and actually conducting reviews of Federal court filings on the day of auction. This presumption is based on the fact that many scheduled auctions are called out as "delayed" or "postponed" due to bankruptcy. Hence, "someone: must be minding the shop. The truth is: this is not so. No prior check by lender or trustee occurs. Bankruptcies are only effective in causing a delay if a homeowner has notification papers delivered to either or both of them. A one week delay is a common push-back while the bandruptcy filing is verified.
The second reason that I have been given by investors for institutionalizing the bad behavior of not checking PACER is that title companies no longer do so. Failing to parse the fact that these insurance companies are offering a different product and using blanket, general exceptions to indemnify themselves against liability, the investors think that they too are able to bury their heads in the sand with no consequences. Luck runs out and the ball eventually lands on red. In other words, they are gambling and will find loss in the long run with such a strategy..
Third, as one goes, so go the others. In other words, if one investor conducts his business in this manner, then his peers tow the group-think line and follow suit. This may be spurred on by the rise of foreign nationals pooling their funds in order to acquire houses at any cost. They often show no care for conventions of investing as they are seeking real estate no matter what. In fact, liens and other encumbrances of record or otherwise will simply be passed along in uninsured buyer sales to unsuspecting "captive" audiences of foreign nationals seeking the American Dream.
Finally, for the real cheapskates out there, the $0.10 cost per search page that PACER charges to a credit card eats away at the bottom line (read: profit margin) for each house purchased.