I agree, if you are a used cars salesman or a pizza delivery driver, you are probably not going to make those levels of commissions.
The sales person does technology sales, sells systems to companies. Just one sale he had brought him around $50k in commission. Depending on what he sells generates different levels of commission. In the case of the large commission I believe he sold something in the order of $2 to $3 million worth of data storage and management equipment. Now your average car sales person doesn't have that level of a sale for one transaction.
For the delivery drivers, they received commission on the volume they delivered, and I personally know how much can be made (not just hear say) as when I was a kid I use to be a delivery drivers helper and made bank as I received commission as well, a smaller commission as I didn't drive or have the appropriate license to drive but still was a great take for someone who was only 16 at the time. Some days we would be at the warehouse before leaving and the warehouse guys would be telling us there is no more room to put any product and we would literally get them to load it in the cab just so we could make the extra money, it would be cramped until after the first couple of deliveries and then we could move the shit out of the cab. At the time they were G licensed drivers with an additional test for air brakes usage. Eventually the company did move up to trucks which required higher levels of a license.
Other friends in sales jobs that do well are in pharmaceutical sales, ergonomic office furniture, and financial products (they call themselves financial advisors but they are really just selling the companies financial products or funds).