If there’s a sign saying there are surveillance cameras or trail cams, cool. I worked for a casino, I’m used to being somewhere that, except when I’m literally in the bathroom, I’m being watched.
Secret ones or ones boarders/anyone can access that are looking at something other than, say, down into a horse’s stall (like Foal Cams where some farms stream the mares and it’s posted that’s what happening? Not cool. Hidden cameras in the arena, paddocks, tack rooms, etc are a no. If you want to record for security reasons, do it, but post. I don’t want to decide I need to change shirts really quick in the tack room after spilling liniment on it and discover the footage on YouTube or learn the owner was watching the whole thing. And I don’t want to know how those folks who can pee in a stall when desperate would feel!