Anyone who intentionally throws away errors because they "got tired" of checking errors, isn't someone I'd want on my team, and their code is not something I'd want to depend on, regardless of the language. Hopefully it would get caught in code review. But yes, it would be nice if go vet or go lint caught this syuff. Luckily, someone else wrote errcheck, and that's good enough.
I've noticed most of the intention error punts in dense code where it looked like someone got tired of repeating checks and only checked the errors which happened while they were working. I'd bet a read-before-overwrite policy on _ would catch mostly infrequent environmental failures (i.e. the kind of stuff which only breaks when you're out of space, file handles, etc.).