If you’re really interested, here is a 15+ minute video that discusses the problems with the retracting door handles, including the common causes of failure and how to fix them. It’s been awhile since I watched the video, so I don’t remember what goes wrong.
They switched to a flush, but “manually ejected” door handle for the Model 3. Aside from being cheaper, there is much less to go wrong. After a few minutes of practice it is easy to open with one hand. Push with the thumb, and then pull the presented lever with the rest of your hand. I could see it as a problem for somebody with arthritis, otherwise I think detractors are just whining.