Very interesting. I have had it happen at Desert Inn and Suites, and at the Candy Cane, but never at the DLR hotels.
That said, I just spoke to the front desk manager at the DLH, and was informed that this is not their policy and that they do not keep a card on file to charge. You are charged for the first night as a deposit. And if you don't show, they keep that deposit. But until you check in, they do not charge your card, and do not have a way to charge since the computer system does not allow them to keep the card on file. (I know about a year ago I asked them if they could just charge it to the card on file as I left my card in the car, and they told me then they didn't have it on file as the computer system didn't allow for security.)
An exception to this could be group sales, such as convention rates. But even then I had to drop out of a convention rate once and was only charged for the 1 night.
I will ask more questions this weekend.