How do American citizens exercise popular sovereignty?

Popular sovereignty is the concept that all power is ultimately derived from the people. This means that every time you vote or express an opinion to a local leader/ politician, you are shaping the way this country is run. The problem? Old while men are the ones with free time on their hands, so they are the ones going out to vote and becoming/ influencing politicians, which makes the national vote a reflection of- not the actual public's opinion, no- but  instead the opinions of those who have lots of free time on their hands... (*cough, cough* white nationalists)

Americans express popular sovereignty every day... kind of.

health care plans in the united states having high costs because they are focusing on providing quality programs for different groups of individuals. the quality of the service is based on money flow received from the members. without this investment, couldn't be possible a constant scientific searching to prevent death and illness caused because of low levels of health investigation. currently, the complaints are not about the highest cost, but about the coverage and benefits to access the necessary health services required by the members.  

besides, if a global health system is established the quality levels will fall down because of the standardized of the health. the access to care will increase but the quality will be low because it depends on the money invested.