Every step you take, you are doing just a slight form of squatting. You experience muscle flexing in the quads ever so slightly. It can be even more intense of a squat when walking up or down hills/stairs. So, there is a lot of particular work that is repetitive going on in the legs. Most of your mini-squatting work is performed when the feet are not that far apart.
So, for people to also go to the gym and squat with their feet shoulder-width apart are just repeating their daily walk/run exercises but in a deeper form. They are essentially still working the muscles in the same way by doing a deeper squat for their walking motion. This will cause a repetitive stress disorder and strength imbalance in the muscles.
Strength imbalances lead to many joint pains and eventually you will need to rest until the pain goes away. It shouldn’t work like that. You need to perform wider stance squats to complement the shoulder width squats that you do every day.