This is a correctly marked up ARIA Radio Button group. However, the scripting incorrectly uses 'focus' to trigger selection.

To see the differences between JAWS and NVDA, do the following:
1. Running JAWS, press Control+Home to move to the top of the page, then press the Down arrow to read through all content on the page.
2. Confirm that nothing is selected automatically using JAWS.
3. Now perform the same test (1) using NVDA.
4. Confirm that selection occurs automatically on the first radio button with tabindex=0.
(The act of reading content causes NVDA to automatically trigger the 'focus' event.)

Note: NVDA's auto triggering of the 'focus' handler matches the functionality of VoiceOver on iOS touch screen devices,
whereas JAWS' functionality does not.