Without a link to a reputable source this is an assertion, but not proof.
The total population of Florida ia ~19 million. If half is of working age, and there is 8% unemployment, that is 760,000 unemployed people. Weekly maximum unemployment comp in Florida is $275. If we take $200 as an average payment, that would be an annual payment of $7.9 billion.
The $100 million you claim for a cost is 1.3% of the annual payments. We only have to catch 1.3% of the recipients taking drugs to justify the cost.
Are you really claiming that 98.7% of the unemployed can pass a drug test?
My personal observation in Oregon is that no more than 20 to 30% of the unemployed around here could pass a drug test.
Even if the program does not pay for itself, it is effective in combating the moral rot that drugs cause in our society.
The “moral” argument is a farce. The real drug problem this country has is in legal prescription drugs, much of which the taxpayer pays for.
That’s where real savings - moral and fiscal - are to be had. If the moral claim is at all serious, that is what we need to be working on, not some marginal percentage of welfare recipients. Just bringing our per capita pharma spending down to OECD average https://data.oecd.org/healthres/pharmaceutical-spending.htm would be $200 billion in welfare payments saved, and it would do so specifically by curtailing curtailing drug abuse.