Today I noticed that radio buttons and checkboxes have different interaction for focus state.
If you look at the example webaim of a radio button you notice that you can not select the next radio button using the same tab-interaction. To select the second option you need to use the up and/or down keys to change your selection (and it auto selects your current version).
However when you want to switch checkboxes you can use the tab-interaction to jump to the next. I find this interaction somewhat strange.
I can understand that you only select 1 of the options of a radio button, but this makes every radio button field for key-board only users mandatory (because the first tab auto selects the first radio), while not every radio button field might be mandatory.
Example: In some signups, selecting your gender/sex is not required but optional. These are mostly Male / Female and sometimes Other. Keyboard only users would be required to fill this information because they can not skip the question using tab.
Am I missing something, or is this behaviour inconsistant with other interactions? Any WCAG experts that can shed some light on this?