One does not follow from the other. Franchisees are independent businesses. Baskin-Robbins would not be involved in the payroll operations of its franchisee.
If a franchisee were getting slews of do-not-match letters from the SSA, if it was paying its employees under the table, Baskin-Robbins would not be the one to catch them. Although, they would certainly notice after the fact, if, say, a franchisee got hit with an I-9 audit from ICE and ended up in the news for having to fire half its employees, as happened to Chipotle in Minnesota recently.