YANBU at all OP, but as a non-horse-owning townie I beg you to put up more informative signs than "Don't feed the horse".
We’ve tried all manner of signs. Nice ones, ones giving explanations, ones with photos, etc and they mostly get ignored.
Do not feed the horses should be enough - people shouldn’t need to know the ins and outs, not their horse/animal - don’t feed it.
My horses are away from public footpaths, but we’ve had people coming onto the yard and feeding them while they’re in their stables, trespassing in fields with no footpaths in them and feeding horses despite clear signs asking people not to. Then they come down to the yard complaining that they’ve been bitten, or shocked themselves on the clearly signed electric fence.
A few times when I’ve intervened I’ve got a mouthful of abuse, told to fuck off, called stuck up, been told people will do what they want or parents complaining I’ve spoiled their child’s fun - what about my child’s ‘fun’ when her horse has to be put to sleep?
We’ve never had such a hard time with this as we did last year and so far this year so I’m hoping that the lifting of restrictions will mean people go back to their usual activities.
I’ve actually found it’s more productive to speak directly to the children in some cases. A few times I’ve intervened when a child is feeding my horses with their parents and I’ve explained directly to the child why they shouldn’t do it and why it’s dangerous and they’re far more willing to take it on board than their adults. A few weeks ago a woman and a little girl were feeding them, when I intervened the woman just gave me a load of shit about upsetting her child. I spoke directly to the little girl, explained that the horses had some health issues and were on a special diet. The little girl was lovely and very sweet, I called my old girl over to the gate, she gave one of her trademark bows, the little girl made a fuss of her and everyone went on their way with the child vowing to tell everyone at school what I’d told her about not feeding horses.