From what I've understood the thing is with carrying any sort of weapon or device is whether or not you could use it; if you're caught unawares there may or may not be time to react.
I had one experience doing home visits where a guy passed me and nodded and I nodded back and then the realization sunk in, did he have something under his jacket?? I walked very fast the last few feet to the car, hopped in and got the heck out of there. If Mr. Friendly neighborhood drug dealer (and I don't know that but would consider it a possibility) wanted to take me out I don't know that I could have done anything or not to prevent it. But trying to be alert, park close to where I'm going, schedule early mornings before things get hopping, etc. could be preventive (and carrying baby toys probably made me appear as not much of a threat to the livelihood of any Mr. Drug dealer types around).
Of course something could happen anyplace, and thinking about how many home visits we did in our jobs, in 20+ years we had some odd situations but nothing life threatening or close to putting our lives in real danger. So maybe the odds are against an attack or abduction and everyday routine happenings aren't what you see on the news.
Being in a park of course is a situation where in a way, maybe more likely to be a place where you wouldn't expect to have to be too concerned about safety. I agree, prevention and awareness are probably best as much as possible.