I'm not sure this is true. Current US federal food and drug law has been in effect since the 1970s (for specifics, I'm thinking 21 CFR 211, which was codified 1979-ish) and it hasn't really been repealed so much as it was never very explicit and rarely enforced, in part because of the difficulty of enforcing something so vague.

Example: The law clearly says, "you must have a written procedure in place to prevent contamination," But it leaves it up to the manufacturer to determine what that procedure should be. In contrast, some of the EU legislation (EUDRALEX) is much more prescriptive: "you must do X, Y, and Z to prevent contamination in a multi-purpose facility."

What little legislation was in place as US law before 21 CFR 211 was worse.

It's also worth noting that much of the US's regulation via agencies like the FDA is actually released as "guidance for industry." Or to paraphrase, "don't be a freaking idiot about things, but we can't legally prosecute you for it if you don't." That's a big loophole.

Consider the legal fiasco that was the trial of the owners and "quality manager" of that peanut company that caused multiple salmonella deaths about 10-15 years ago. Their QA manager's legal defense was literally: I'm not qualified to do my job and should never been hired. 21 CFR says that "employees should be qualified to perform their jobs." What does that mean? Should she have a degree in biology or chemistry? A degree in early childhood learning and k-12 education? On the job training on the day to day of the peanut factory and what to do if you have in infestation of birds? Beyond that, who is in charge of making sure she's qualified? The regulations are unclear, and in the system that's been in place for 40 years, all of those questions will be hammered out in the randomness of court and in the worst way possible. Like so.

https://www.foodsafetynews.com/2020/02/ill-fated-quality-control-officer-for-peanut-corp-of-america-freed-from-federal-custody/#google_vignette

I'm sorry - I could write a whole freaking book about this.