The Bitcoin white paper says:
Completely non-reversible transactions are not really possible, since financial institutions cannot avoid mediating disputes. ... Transactions that are computationally impractical to reverse would protect sellers from fraud, and routine escrow mechanisms could easily be implemented to protect buyers.
My understanding is that Satoshi decided to protect the sellers and this seems to suggest that he thought that sellers are more vulnerable to business fraud. (He surely didn't mean that buyers are not important, but his design decision favors the sellers, I think.)
Is there any existing evidence, report, or statistical data that support that sellers are more vulnerable to fraud?