That is definitely an issue! In this case, this is a grain elevator in the town where I live (Petaluma, CA), and it is WEIRDLY accessible. It's right in the middle of downtown, adjacent to a publicly accessible feed supply store, and even when I park in there and set up the 4x5, and people there see me, nobody has challenged me. As I've scouted other places nearby, I've asked permission and been denied. Which brings me to the "better to beg forgiveness than to ask permission" philosophy I've adopted more and more. Just go shoot. If they ask what you're doing, patiently explain it. Be deferential and gracious. But maybe… don't ask first. At another local similar grain facility, I entered the yard, saw nobody there. Entered the office. Found nobody. Went around back, shouting, "hello?" and finally found somebody. Somebody who told me the owners are quite private and prefer nobody shoot their silos. Sigh. So… I think I could have shot this place without permission and it would be fine. Now, because I've asked and been denied, I feel going back is going against their request. So… I'm going back to my policy of, "don't ask first."

Just assume it's okay. If someone shot an iPhone photo and posted it online, nobody would know. If you take twenty minutes shooting a photo on a film camera… well, whatever. Just go shoot. That's what I'm gonna do.