Was about to write the same. The three examples I clicked on - tabs, accordion, and menu - didn't work via keyboard.
All of these are fairly simple show and hide interactions that are easier to use, build and maintain when done with javascript, with all the content shown if JS is turned off, not fully loaded or broken.
The accordion can work via keyboard with some styling changes, e.g. position or clip checkbox instead of display:none, add visual indication on :focus. I didn't check the others but their accessibility may be similarly correctible.
Of course for accordion in particular it would be better if the pure HTML solution of using <details> and <summary> elements was supported in all browsers. They're already in Chrome and Safari and will come out from behind a flag in the next Firefox version. A polyfill for IE etc. can bridge the gap.
True, yet when examples like these are added without basic keyboard accessibility in mind they can get added to projects in the same half finished state.
How many sites using Meyer's reset didn't add focus styles to links? Even with the comment /* remember to define focus styles! */
It's not the fault of the original developer but it certainly helps to have more robust examples.
All of these are fairly simple show and hide interactions that are easier to use, build and maintain when done with javascript, with all the content shown if JS is turned off, not fully loaded or broken.