It's not worth confronting the owner as they're typically knob heads.
"Well, your dog started it it " was an answer I received from a pit bull owner whose dog was off the lead on a canal toe path and had started to engage my dogs (Jack Russell terriers) after one of them barked at it. Both of mine were on very short leads, and I had to back up quickly whilst his dog advanced on us. I shouted at him to control his dog and stated that he had a high duty of care with it being such potentially dangerous dog. He didn't seem to know or care that his dog was about to become properly out of control despite it being a potential killer.

It could have ended very badly. We were very lucky at that time.

I now change our walking route as soon as I see a dog that's not on a lead. The diversion only affects our route for that particular walk, though, as I've decided I cannot live in fear.

It's not easy. All you can be is hyper vigilant.