This confusion is extremely common. I went through the same situation and only understood it properly after reading
Roofing Disposal Fees The guide explains that disposal costs depend on much more than people realize — the weight of old roofing materials, how many layers are being removed, and local landfill pricing rules. What surprised me most is that some roofs weigh several tons, and dumping fees are charged by weight, not by “job size.” Once I understood this, the price differences between contractors finally made sense, and I could see which quotes were transparent and which ones were vague.