It’s a design issue. Georgena Terry has a series of videos on bike design for small people. Her videos explain the problems very clearly. My wife has had two Symmetrys. One was the 520mm front/622mm rear. The one she has now has the same sized wheels in 650C (571mm) size. The 650C size wheels makes for a smaller frame all the way around. She has found it very comfortable. The former was the first bike she has ever owned that actually fit. Terry’s ideas really work even if they are unconventional.