There is very basic, simple reason for it and has nothing to do with the company being evil. I believe it is possible to use Roundup safely and the reason it gets into our food is misuse.
(disclamier: "possible to use safely" does not mean it is reasonable to expect people to do so on their own)
Roundup kills plants. It does it by breaking roots of the plant which causes the entire plant to dry out.
For some crops (like wheat), it is very beneficial to harvest the crop after it dried out. But plants do not care about calendar and do not necessarily all dry out at the same time.
So what farmers do, is to spray their crop just before harvest. It all dries out nicely and uniformly and can be harvested all together at the same time with minimum spoilage. It can also let them schedule harvest on various plots to happen at different times rather than all at the same time. It can also allow to force harvest earlier if you, for example, predict bad weather. Or if you want to go for vacation.
This is not how Roundup is supposed to be used but this is very popular "hack".
(disclamier: "possible to use safely" does not mean it is reasonable to expect people to do so on their own)
Roundup kills plants. It does it by breaking roots of the plant which causes the entire plant to dry out.
For some crops (like wheat), it is very beneficial to harvest the crop after it dried out. But plants do not care about calendar and do not necessarily all dry out at the same time.
So what farmers do, is to spray their crop just before harvest. It all dries out nicely and uniformly and can be harvested all together at the same time with minimum spoilage. It can also let them schedule harvest on various plots to happen at different times rather than all at the same time. It can also allow to force harvest earlier if you, for example, predict bad weather. Or if you want to go for vacation.
This is not how Roundup is supposed to be used but this is very popular "hack".