Final answer:
Amazon may support the Marketplace Fairness Act as it levels the playing field with physical stores and they have the infrastructure to handle tax collection efficiently.
Step-by-step explanation:
A large online retailer like Amazon.com might support the Marketplace Fairness Act of 2013, which requires online merchants to collect sales taxes from customers in other states, because it helps create equal competition with brick-and-mortar stores. This measure ensures that online businesses cannot undercut local businesses solely based on tax advantages. Additionally, for a company as large as Amazon, the infrastructure to collect and manage sales taxes across various states is already likely in place, which minimizes compliance costs associated with this regulation.