I can answer some of your questions.
Regarding the cost: the state pays for it until a person tests positive, after that the testing is paid for by the applicant. When someone is charged with drug use and probation requires testing the person has to pay for it themselves no matter what kind of financial hardship it causes-SNAP could follow same protocol. The state could probably recover the costs of drug testing through what is saved by the elimination of benefits to drug users. It’s about $40 per test vs hundreds per month on groceries.
As to kids starving without food stamps, there are already plenty of charities and government programs that feed kids away from home. Free breakfast and lunch at school, plus meals at the park and the charities that have the backpack program for kids in need to secretly bring home food for the weekend. If kids are starving with all of that due to their parents’ selfish drug use then they don’t deserve to keep their kids.
It never used to be easy to be slothful in our society; people who were struggling would put their kids, not their drug use, first. We should make it extremely painful for parents who neglect their children due to drug use.
It seems that the end result of this would be an increase in crime, as many drug addicts would likely turn to crime instead of gainful employment.