It is an honesty/respect thing, if you don't live there you shouldn't fish there if they ask you not to. I don't live in any of those neighborhoods but I do live close and run around and past many of those small ponds and most of them have signs. The parks are for sure public and South lakes(eureka) is designated as a neighborhood fishery and is stocked regularly.
It is my experience with all the growth in the Denton area, as soon as people find a new public pond, it is talked about on social media and very quickly becomes fished out. There are several that I used to fish but no longer do because of all the pressure, Northlake fits that description for me. On any nice day that stretch chickenman highlighted will be fished very hard many times over. Having said that, the fish are gun shy but there are still some to be caught and the grass and pads are green and healthy!
Good luck to you!
See you on the lake and have a great day!