said by CylonRed:
Because the ISP does NOT want to deal with issues when the customer has screwed up the modem.
"Customer - I didn't do anything to the modem".
Tech goes out on call -
Customers screwed up the modem.
I have seen it in just the reverse.
"Customers complains to ISP about persistent network issues."
"ISP dispatches technician, after several months of reporting issues, who also cannot establish a solid connections."
"Tech provides customers new modems to satisfy network engineers."
"Replacement modems continues to have problems."
"Network engineers mystified - problems found at CO which resolve a couple issues. But problem continues and the resolution cut back speed until problem stops. Because the network is severely oversold."
Therefore it is reported as customers caused issue, but the ISP didn't have any issues. Note: Customers is plural.