I don't know what mirror switch is, but XS4ALL also has Netflix boxes. I didn't actually realize that it might be a special thing: why not reduce your transit traffic? But now that you mention it, yeah, murica.
And XS4ALL is also fine with you using your own hardware, but so are all German ISPs by law so that's not super special.
It's also not rocket science to clone their MAC and do the authentication afaik. But I've never had to do it so I'm not sure if it seems easier than it is.
In Germany before that law, they made sure you wouldn't get the credentials to roll your own. There were some tutorials around how to extract your PPPoE credentials from certain cheap DSL routers, but many were fixed over time, so if you really wanted to do it, you had to open the box and read the EEPROM by external means. Cable modems always have a certificate baked in and were tied to your account, so just cloning the MAC didn't help.
Some American ISPs have realised they can shake down Netflix for cash by refusing to install caches, connect at peering points and suchlike until Netflix pays them.
Some Americans can only get broadband internet access from a single company, so they don't have the option to move ISPs when their Netflix access is degraded.
Upon re-reading I see how that sentence was badly written. I meant that there is at least one fairly large country (a neighboring country even) that mandates this, so I don't consider being allowed to use my own router very special.
And XS4ALL is also fine with you using your own hardware, but so are all German ISPs by law so that's not super special.