"Your run of the mill MITM" is no MITM at all, in my experience. When I connect to the internet at coffee shops and airports and even my employer with a Blue Coat MITM device and a root cert installed everywhere, HTTP is generally not tampered with at all, even though it easily could be tampered with. A small percentage of the time, some sites are blocked entirely; there's a static page with no JavaScript replacing the site. A few years ago my cell phone provider re-compressed images but made no semantic changes / introduced no attack surface from a third party. Tampering every page as standard behavior is definitely worse than what I expect. What is your expectation of "run of the mill MITM"?
Furthermore, MITM is either in exchange for something of value and therefore desired by the user (regulatory compliance at work, perhaps free wifi at coffee shops, perhaps better performance for older cellular networks), or it is an attack. The existence of MITM in general is not normal. Why should Vodafone be MITMing at all? Why is "as attacks go, I've seen worse" a defense?