Yeah, in the USA outside of some rare exceptions, anything that makes claims of killing or controlling a pest, whether weed, bug or microbe, becomes a "pesticide" and enters a realm with a LOT of expensive regulation and testing on efficacy claims, target safety, and non-target safety. Most companies will quickly opt out of that shitshow.

For example, you can't just decide to sell acetic acid (vinegar) claiming it's a weed killer without following the same rules as the megacorps. And it's also why if you took jugs of "unregistered" grocery store vinegar, and applied it as a pesticide, you can get in big trouble. Now no one will really care if you do it as a homeowner unless you get really carried away, but if you were a commercial applicator of some kind then expect trouble if caught. This is what that warning "It is a violation of federal law to use this product in a manner inconsistent with it's labeling" stamped on everything means.

This leads into weird scenarios where things like some ordinary phosphorus foliar fertilizers have a mild antimicrobial effect (I believe mostly against fungus, but I don't recall clearly) and everyone knows it. However no one can make that specific claim as part of a sale, because then the cheap fertilizer becomes an expensive pesticide. So an agronomist and farmer just wink and say "yeah, those plants with a fungal outbreak could sure use some nutrition to help it's vitality". Note that on it's own the phosphorous isn't likely to control anything, but can definitely help in combination with a real control, or delay how soon control is needed possibly saving a regulated spray.

I believe the EU recognizes one of the phosphorous fertilizer forms as a pesticide, and thus growers here cannot apply it if that is where the crop will be exported.

To be clear, you absolutely do NOT want companies to apply things willy-nilly as pesticides. They have repeatedly demonstrated the lack of ability to self regular and as such will always race to the bottom of irresponsibility. But there are definitely a lot of seemingly brain dead consequences involved. However it makes more sense when you consider the long term environmental and pest resistance consequences involved.

Silver for example has implications that need to be watched when in constant contact with food and thus ingestion [note 0] and buildup of silver ions in the environment [note 1]. Organisms can and will become resistant to silver and copper, especially if one applies constant heavy selective environmental pressure. As such, our laws are in this instance are in fact doing what they were intended to do, regardless of obvious failures in other areas of concern.

[note 0]: Let's just ignore for a moment that silver is remarkably safe and doesn't seem to act as a disruptive "heavy metal" because it's bound safely so quickly. Even in extreme amounts taken by fanatics, tissue pigmentation is seemingly all that happens. Meanwhile the plastic used for the containers that is in contact with your food is likely far worse in comparison.

[note 1]: Let's just ignore the massive failure of regulating the effects of all the other antimicrobials, microplastics and pharmaceuticals dumped in the water supply...