I don’t have boy parts so this may be different, but I’ve shaved my legs and pits/bits for like a real long time now, and while I’ve cut myself shaving my legs an absolute ton, I’ve never once cut my pits or bits.

I am absolutely not more careful, I just stopped using a blade on my legs and got an electric. Shaving is a pain and I hate doing it, so I’m not careful. But I do have men’s face razors for my shaving needs because they are better for the contours.

I’m convinced only large patches of flat or slightly curved skin -or with edges, like chins or behind the knees- are really vulnerable to the shallow angle you need to get a good slice. You just don’t get that with the short strokes needed for pits and bits. That’s probably also why barbers back in the straight edge days did lots of tiny strokes.