A recommendation may rely on assumptions about location, exposure, existing condition, and intended use. Those assumptions should be explicit. Otherwise, the owner cannot tell whether the proposal was prepared for the actual property.
What to do next
Ask the contractor to identify the information used and any unresolved questions. Obtain manufacturer clarification where relevant. Compare bids on the same exposure and building assumptions rather than treating differing product recommendations as merely different preferences.
Related Perkins guidance
Contact Perkins Roofing to discuss your roof and the appropriate next step.