An op shop, stocked entirely with donated second-hand goods and staffed largely by volunteers, functions as a small but genuine local economy running almost entirely outside the ordinary retail system, keeping usable clothing, furniture, and household goods circulating rather than heading straight to landfill after only brief use.
The proceeds from sales typically fund a charitable cause directly, which means a routine purchase, a secondhand jacket, a set of plates, doubles as a small, low-effort act of community support that costs the buyer little beyond the ordinary price of the item itself. Few things about this are complicated, which is part of why they are so often overlooked.
Beyond the transactions, an op shop tends to function as a genuine social hub for the volunteers who staff it, many of them retirees seeking regular purpose and company, which means the shop is doing quiet social work well beyond its stated charitable purpose alone.