State tax filing

Why can’t they just not tax me in Pa? On the website for PA It says non residents who generate income in the state where they work and live employers do not have to withhold taxes from the state they are in business. This is confusing but PA DOR says this:

 

A non-resident employee who is required to telework full-time from home in another state should treat his compensation as non-Pennsylvania source income even if his employer is located in Pennsylvania. In those situations, the employer is not required to withhold on the employee's compensation.