What's the ISP's motivations towards preventing BYOD? If they're desperate for the $10 per month box rental, I'm sure they could just levy a $10 per month BYOD

What's the ISP's motivations towards preventing BYOD? If they're desperate for the $10 per month box rental, I'm sure they could just levy a $10 per month BYOD "support fee" to make equal, but it sounds like in some places they're charging way more as a penalty. I know some of them were very aggressive about using home routers to provide coverage for roaming Wi-Fi, but that doesn't seem as big a push as it was. I suspect this corresponds with a lot of them getting into the MVNO business lately. Do they result in a disproportionate volume of support inquiries, or maybe ones that they can't just dispatch by trying to send a remote-reboot signal down the line? I could see addressing that by moving towards a fee-for-service-call model if you need to call the "custom configurations" hotline.