There are several possible reasons for this: 

  1. The shopper may be using a VPN. VPNs allow shoppers to route their internet traffic through a proxy address in another location or country. VPNs are commonly used to evade country-based access limits to websites. 
  2. The shopper's ISP may be relatively new and the geolocation databases may not yet have accurate information for the ISP's IP address range.
  3. There may be errors in the geolocation databases or the shopper's ISP may have provided the ISP's location instead of the location of the shopper.