Accountant refuses to track COGS for my courier business

I own a small courier business and recently asked my accountant why he doesn’t track COGS (Cost of Goods Sold) for me.

I use my van for deliveries about 90% of the time, and I also hire subcontractors, pay for maintenance, etc. Since I don’t manufacture a product, I provide a delivery service, I asked if it makes sense to categorize those direct costs as “Cost of Service” rather than traditional COGS.

When I pressed him on why he won’t do it, he said that COGS is more useful for larger businesses to see profitability, and that tracking it would be “too much work” for me. He also mentioned I could track it separately on the side if I wanted to see the numbers, because it “doesn’t impact the P&L.”

The thing is, I already keep a detailed mileage log with all the necessary info. I’m honestly annoyed. He keeps pushing back, but I feel that understanding my true direct costs is essential to knowing how profitable my business really is.

Am I wrong to insist on this? Or is he giving me bad advice?