How is that so? Politicians have a way to destroy/privatize public service whether it's self-funded or not, just like they destroy/ban private associations doing too much of a job for social justice (such as armed bands expropriating the bourgeoisie to feed popular districts, which was common throughout the 60-80s).

Famously, french social security (healthcare), unemployment and pensions are more or less self-funded (they all have their own line/column on taxes papers), yet the previous 3-5 governments have been relentlessly reforming those essential public services in order to render them useless. It's also important to note that in most instances of such reforms, the government will point out some money is missing to fund the service, which :

- is only partially true, as insane amounts are spent for their disserving bureaucracies, managerial class, and control apparatus, all of which we would do better without

- is still partially true, but benefits fraud represents in all cases less than 1% of participation fraud, where the biggest companies are the ones evading to pay their dues... so if law enforcement were to crack down on big corporations fraud instead of political dissent, the problem would be solved very easily

You are correct, but if the service is self funded via operational fees it is better able to stand for longer - which gives a chance that whoever is harming them will be voted out and someone else will do better. Though we have ample experience in the US of long term neglect from both parties, the more you are self funded the harder it is to do that. If you are not self funded as soon as someone cuts your budget you have to cut service, but if you are self funded you can ride out those winds better. (though COVID like things will harm you no matter what)

There is no great answer here, but I still believe that self funding of operating costs is the best answer.