Yes, it’s to be expected with all validation tools, most of the time, no one passes all errors and warnings on these tests, nor is it even important to. In fact, worrying about these tools too much can actually lead people to do things to their sites just to appease the tool for that 100% that’s not necessarily good for their visitors.
Google itself doesn’t pass W3C validation:
These kinds of tools are useful for finding major problems, like broken code, but warnings should be taken lightly and often considered negligible. The more you use them the better you’ll get at spotting things that require action.
Also, if you don’t want to go digging around in the code, there are plenty of SEO plugins to try: