Of course there were a few people who were missed, but usually the reason someone cannot be found is that the name was misspelled (the census was taken orally) or the indexer could not read the handwritten name. It might help if you gave us some basic information about your grandfather (name, age in 1930, place where you think he was living at the time, was he single or living with his family).
Dear Mr. Wierski,
Thank you for posting your request on History Hub!
We searched the National Archives Catalog and located the Population Schedules for the 1930 Census in the Records of the Bureau of the Census (Record Group 29) that may contain a record of your grandfather. Very few schedules have been digitized. For access to the non-digitized schedules, please contact the National Archives at Washington, DC - Textual Reference (RDT1) via email at firstname.lastname@example.org.
Due to the COVID-19 pandemic and pursuant to guidance received from the Office of Management and Budget (OMB), NARA has adjusted its normal operations to balance the need of completing its mission-critical work while also adhering to the recommended social distancing for the safety of NARA staff. As a result of this re-prioritization of activities, you may experience a delay in receiving an initial acknowledgement as well as a substantive response to your reference request from RDT1. We apologize for this inconvenience and appreciate your understanding and patience.
For information about the 1930 U.S. Census, see the Decennial Census Questionnaires & Instructions.
You may wish to search Ancestry.com for the U.S. Census. There may be a fee for using Ancestry. Instead, some of the images from Ancestry are available for free on Family Search or at your local library. Many library systems subscribe to these sites, making them free for their patrons.
In addition, the NARA’s How can I search the Census Records? web page may be helpful.
We hope this is helpful. Best of luck with your family research!