In reality, those sections outline that The Secretary (who is presumably defined elsewhere) can take surveys as a part of their census process. It is Section 221 that requires you to respond:
Whoever, being over eighteen years of age, refuses or willfully neglects, when requested by the Secretary, or by any other authorized officer or employee of the Department of Commerce or bureau or agency thereof acting under the instructions of the Secretary or authorized officer, to answer, to the best of his knowledge, any of the questions on any schedule submitted to him in connection with any census or survey provided...
That's just a crock.
Oh, sure, census information is useful and all that. It's just the principal of it. I guess I'll have to ask the nice lady who came to my door for some evidence that she is an authorized officer or employee of the Deparment of Commerce, or a bureau or agency thereof acting under the instructions of The Secretary.
Heck, I'd pay the $100 if it weren't for Title 18, Section 3571 (allegedly Section 3559 as well, but that seems to deal with imprisonment and not monetary fines). With it on the books, the "not greater than $100" fine becomes "not greater than $5000" fine. That really blows.