When I've worked on this type of task it's been an issue of scale.

They can eBay camper trailers, trucks, ATVs. Each is different enough not to use average costing. Some have significant cost. Anything on hand is tracked as inventory if not sold over the year end, to match revenue to the sale date later.

I helped a business handling secondhand children's clothes and toys. They use average costing when they take inventory, They have a brick and mortar location, so they have a significant count of items on hand over the year end.

I helped a water utility. They have an inventory of system repair parts, some of which will be charged to the customers when something is used (meter, valve, pump). These are all deducted in the year of purchase.