Google and the Census both don't require individual users to signup to access their data.
However, both require that their users signup for an API key to do automated querying. (In fact, Google charges for its Web Search API now.) It's pretty standard for any API to want to be able to identify and potentially meter usage.
(3B) Census data on some topics can move markets. If someone hacks to get a five minute lead time, the key policy gives them a start on figuring out who and maybe how.
Re:The US Census now has an API
by fennecfoxen on Thursday June 07, 2012 @01:40AM
(#4077756)
Right. Because if I hack a website I'm totally going to log in with a totally real set of credentials traceable back to me.
Besides, this is the 2010 American Community Survey. Pretty sure it's moved all the markets it's going to move by now.
I can imagine only 3 reasons for this: (1) they want to make you agree to the Terms & Conditions, (2) it gives a way to choke off a DDOS attack that makes repeated complex queries, or (3) the census bureau wants to track how you are using its service.
The key is indeed easy to get, but I observe that Google would have exactly the same concerns as 1,2,&3 above, yet they somehow manage to stay in business without making their users sign up to do a web search.
The federal government always makes things a little more complicated.