"If I take my dog for a lead walk, we walk round the neighbourhood, on pavements, or somewhere where all dogs are on leads."
Well firstly, it's 50/50 round here whether a dog on a pavement is on lead or not.
It doesn't leave me much room to get out of people's way either, you get things like there's a dog coming on my side of the road and a car coming so I can't cross over and I end up literally trapped there because the oncoming owner doesn't stop their walk (nor would I expect them to) to wait for me to have the right timing to cross the road.
Some days all his walks are lead walks because I don't have time to drive for an hour as well as walking him, so that'd mean days could go by on just pavement walks...he still likes to sniff and explore, he can't do that the same.
Gardens have dogs in them...and there are whole streets I can't walk down because dogs rush at the fence barking...which sets mine off.
I don't go to things like parks where there will be loads of dogs off lead...but if there's somewhere to walk, the chances are that someone else will think that's a good spot to walk as well, so there are very few places where there's likely to be no dogs at all.
The only places where there would be dogs that are supposed to be on lead are children's play parks - there's no way in the world I'd walk him there, lol.
So I do pick as quiet places as I can, I purposely walk in heavy rain when I can, I walk late at night...In the dark, with a torch and a friend with a friendly dog to go in front if me when I can as well, lol.
But it's still an issue that strange dogs come bounding over sometimes.