However, it's NOT true that you can't sign up for a free account at Ancestry.com without doing the free trial. Here's how.
Step 1: On the home page, click on "Search", NOT the "Start Free Trial" button (shown above).
Step 2: Type a name into the search fields, John Smith will do fine. No need to put dates or places into the fields (shown above).
Step 3: The search results will be listed and if you click on any of the 1940 Census results (or hover over any of them and click on "Register for a Free Account" in the pop up window - shown above), it will prompt you to create a new account (shown below).
Step 4: Fill out your name, email, and a password to get instant access to free collections at Ancestry.com, no free trial, no credit card necessary, no strings attached. Below is a screen shot of the example record I can now view with my new free account, created without any credit card.
Granted, keep in mind that the free collections are few compared to their total database, but Ancestry.com frequently provide all or certain collections available for free for a limited time. At the moment, they are making their entire database available for free from December 26-29, which is what prompted the complaint that you can't make use of it without going through the free trial, but now you know that isn't true, you can take advantage of all their free offers from time to time.