It might not be that one reason, but could it be something like the following two? Because that would be practically equivalent in terms of unacceptability:
1. Customer IP is in a high risk location, and
2a. Vendor rarely does business successfully with people in that location, OR
2b. Vendors around this region don't usually do business successfully with customers in that region.
("Does business successfully" here was meant to both encompass lack of transactions as well as lots of unsuccessful transactions; I'm asking about both possibilities.)