The prosecutor specifies the terms of the plea bargain.  The accused has generally been plastered with a whole menagerie of felony type crimes with prison terms up to life so of course the accused would be stupid not to accept the plea bargain to some much lower charge (regardless of guilt or innocence).  Calling a plea bargain admitting guilt is like saying that someone who has a gun at their head and told to admit guilt or die is actually admitting guilt.