No, it really isn't. Even in our world thinking Internet == TCP/IP is a faux pas, roughly equivalent to thinking Internet == WWW. Legally speaking I suspect the term borders on meaningless. Obviously a company offering "internet access" must do something to discharge their contract but I seriously doubt you could ever nail them on this.
And if you could and did today, in a month the contracts would be rewritten anyhow, making this a completely moot point.
Thinking TCP/IP = IP is also a bit of a faux pas. No fair changing the terms I used out from underneath me and then complaining.
Further... again, go check your contract for your home provider. I'm quite confident it doesn't promise to "serve IP packets", let alone making any promise whatsoever to serve them without modification. Don't lose sight of the context here... pedanting about what protocol is in use isn't going to change the fact that none of them are probably mentioned in your contract.
And if you could and did today, in a month the contracts would be rewritten anyhow, making this a completely moot point.