Made to fit the gap, not the other way round
Off-the-shelf gates are made to a standard size. Openings aren't. These were built to suit the gap they were going in, properly braced so they can't drop or sag, and hung on heavy galvanised hardware that will still be swinging sweetly in ten years.
A gate that catches on the floor every time you open it is a job that wasn't finished properly. These swing true and latch first time.