Dude, do you seriously think that corporations of the Gilded Age were just about to voluntarily improve working conditions, stop selling adulterated products, etc? Really? What color is the sky on your planet?
By the same argument, if drugs were legalized tomorrow, you would claim that everyone would run out and start doing heroin.
-1, Strawman argument. Of course, I wouldn't claim that. I might, entirely reasonably, claim that some people would, and that those people would be harmed. Whether the benefits of drug prohibition are worth the costs is another argument that is entirely off-topic here. Relating this back to the topic at hand - no, I don't claim that getting rid of, for example, USDA meat inspections, would immediately cause all meat to spoil spontaneously. You're right, that's just stupid (which is why I don't claim it). But we know from freaking experience that without any inspection program, some companies ABSOLUTELY WILL sell tainted meat, and customers have essentially no way to know which products are safe and which are not. As a result, many people will be harmed. Unlike the drug prohibition issue, I don't think there are very many people who would argue that the benefits of the inspection program are not worth the costs.
That's the problem with big government supporters--they don't think. They want someone else to do it for them.
And this is the trouble with libertarians - they substitute ideology for thinking.