Why Would Rapists Plead Guilty?

The Government are proposing reduced prison sentences for offenders who plead guilty.
A rapist will only plead guilty in cases where evidence is overwhelming and a conviction is likely.
Figures show 90% of attacked women who come to rape crisis centres don’t report the attacks to police.
And out of every 100 women who do report rape, only six of them will see their attacker convicted.
In a society where rape is a low-risk activity, why would rapists plead guilty?
Knowing their attacker would be released early would make victims fearful, feel justice has not been done and that their trauma has been trivialized.