Similarly why a robust welfare state is preferable to charity. Charitable giving is free to discriminate and there's no mechanism to try and move it towards those who most need it.
If you give charity to someone on gofundme, what charity ever verifies if the person actually needs the money?
The government has no incentive to reduce or even investigate this type of fraud. Enforcement is selective at best.
There are no mechanisms whatsoever to force Bob the billionaire to do a god damn thing with his own money, other than to give the billionaire more tax breaks.
I also used to work in certification for government benefits, and I can assure you there are, in many cases, safeguards and verification.