The entire premise of libertarianism rests on the notion that the world will stay still long enough for market forces to weed out the baddies. Government can sometimes be the better solution because regulations can respond much more quickly to baddies (e.g., I can inspect the restaurant within a week of its opening, or we can wait 6-12 months for enough people to get sick and for the restaurant to develop a bad reputation). Without regulations, the restaurant can just close its doors if it develops a bad reputation, sell its assets, change its name, go somewhere else, and repeat the cycle.
The point isn't that "government will solve any of this", it's that laissez-faire economics can't. Bad actors can skip from exploitation to exploitation -- if there would be less government, then everyone would need to look out for themselves all the time and there would be less social trust, with all the attendant effects.
The false assumption a lot of critics to libertarianism (or nearly any political philosophy) routinely make is that libertarians believe their proposed system would be a utopia with no violence, no "baddies," no market inefficiencies or market failures, etc. Granted, some libertarians who aren't really educated in the political philosophy probably do claim that. But I don't. I certainly don't think that a pure free market would solve all problems. I just believe there would be more prosperity, less poverty, and less violence in a society without a government than in a society with a government.
Libertarians often claim that laissez-faire will always do better than intervention. From the above, it should be relatively obvious that depending on the government and depending on how non-stationary the economy is, laissez-faire could work either quite well or exceptionally poorly.
It's the possibility that laissez-faire could do a much worse job than regulations that libertarians refuse to accept.
The point isn't that "government will solve any of this", it's that laissez-faire economics can't. Bad actors can skip from exploitation to exploitation -- if there would be less government, then everyone would need to look out for themselves all the time and there would be less social trust, with all the attendant effects.