Can someone explain insurance pricing?

I used compare the market to see how much it would cost to insure the CBR600.

Assuming I can’t use the NCB I built up in NZ it came out at £820. Ouch. Exact same details for the more expensive ST 765 RS - £540.

Then for a used GSXR 750 worth around £6…just £340. Despite the GSXR 750 being quite a bit more powerful and having zero safety aids. Even a secondhand GSXR 1000 is cheaper than the Honda.

Can anyone explain?

I love the GSXR and have had two. If they sold them new with cornering ABS I would probably buy another.