My DOCSIS service provider turned off encryption. That's likely due to the certificate expiring on a popular modem brand. Key management is hard, certificate management is hard. Especially when they don't care about security. The encryption was only DES to begin with instead of AES which is supported in DOCSIS but few service providers bother.
Anyone who has the tools to sniff DOCSIS can eavesdrop on my provider's nodes and hear the incoming leg of phone calls.