This is in no way a judgement of anyone who would take alternative actions but I've been trying to think what I would do if my husband didn't come back from a run.
First, I'd probably think he was taking a while and not think too much of it. I think it would take at least three hours before I became concerned enough to send him a text. If it was very hot I might be a bit more concerned. I'd also not know exactly what direction he'd have gone in at least some of the time. He tends to run where his whim takes him. He doesn't take water. He's once got lost in a bit of bush land I know better than him and I've talked him back to a path that would take him out - with his phone at 2% charge, so the possibility of his phone having gone flat, if he didn't reply, would be there too. When would I call the police? I don't know. Definitely by later afternoon, if not sooner. Possibly I'd go look first if I were sure of his route. My first concern would be accident or unexpected medical problem. I haven't actually been in this situation, so don't know exactly how I'd react, but that's what I think I might do.
If he was due to meet someone and they told me he hadn't come, I'd get onto things a lot faster. Not showing up would be out of character and my mind would go straight to accident or medical issues that might have cropped up. I wouldn't ignore that, as SM's family and friends didn't.