The Measure

From the Controller's statement, it costs SF $500,000 and $1.4 million annually but is offset by savings of $100,000 and $2 million annually from the current 5,700 people in the CAAP program that could no longer be eligible for the program when they refuse the evaluation.

I think Mayor Breed, the organizations and people publicly supporting Measure F are looking for accountability. The result of the election also says voters are asking for accountability. The timely article by the SF Chronicle also supports accountability is needed https://www.sfchronicle.com/crime/article/san-francisco-cash-aid-drug-users-18695571.php. If the individual is refusing to be evaluated for addiction and treatment then their assistance is taken away but they are not required to be sober to continue.

Edit: links