Reasons why people are in pain despite medicine

Just curious to know why so many people are in pain? With an assortment of treatments available are people finding it hard to access them because of cost, poor advice, incorrect or meds that don’t work, motivation to get better? I’m in pain right now as I’m waiting to get an MRI to see if I qualify for Biologics but before that, Naproxen SR was doing its thing and made me feel great (before it just stopped being effective).