I see it different and the practice of not having your own transport system and relying on a facility to have one is about ETHICS. Ethics is about what is morally right or wrong and we can't even get DJs to agree in this one little situation, They choose to spin it off to a bad business practice or some other excuse.
Why would someone consider over charging a customer a ethics problem but scoff at the idea that not having the right equipment to do their job is not a ethics problem. Shaking my head in disbelief.