Perhaps small or toy companion dogs would be fine with on lead walking to heel. Larger athletic dogs would need running in safe areas. It's not hard to train young pups around meal times, and recall training from day one, in the home and garden with a game hiding and calling them to you, lots of fuss and a treat.
Get an OS map and discover you local area, you may find there are plenty of places where dogs can be free run for hours. There will be few people there, and if you do see anyone they will,probably be running big dogs too.
Leave the smaller public parks for the people who have the small companion dogs who tend to stay on the flexi leads.
The two dogs living either side of me don't know what a lead is, they never go out of their yards, one is not allowed to use the garden.
So if you don't want to, or are frightened to, let your dog off the lead, then get a low energy dog that will be happy with this limited form of excercise.
I agree with Iam64.. Mind games too.