Why do roofers charge so differently for the same job?

A flat roof and a steeply pitched roof with multiple valleys are not the same job. Steep roofs require more safety equipment, take longer, and pose higher risk. A contractor charging more for the steep roof isn't necessarily overpriced; they're pricing the actual difficulty.
Material choice matters hugely. Asphalt shingles, metal, and tile all cost differently. Cheap shingles wear faster. Some contractors only use premium materials and charge accordingly. This isn't always bad; it's a business choice.
Labor and site factors
Your region's labor costs affect price directly. Urban areas and regions with high cost of living see higher quotes. Local supply chain access also shifts costs. A contractor who sources materials locally may beat someone importing everything.
Old roof removal is labor intensive. Some quotes include it, others don't. Ask explicitly whether quotes include hauling away old material and debris cleanup.
What to compare
When gathering quotes, ask each contractor for the same scope: same material grade, removal yes or no, warranty length, and timeline. Once all quotes specify identical work, differences become clearer. See our guide on hiring a pro to learn what questions unlock honest comparisons.