But if an attack can work on you using my network, it is also an attack that works on me surreptitiously rerouting your traffic onto my network. Basically undoing HTTPS.
Also, what I'm talking about (MITM proxy on a private network), it's not sneaky -- you will get unsigned cert warnings. If you are using an employers device, you won't see warnings, but can examine the SSL certificate. You should also assume that you are being monitored.
No you wont. Bluecoat now has a CA Cert root key signed by Symantec. If they issue a .google.com or .gmail.com ssl cert you will _not_ get an unsigned cert warning.
And explain to me how to connect to, say, my internet banking without using "a private network"? Every single hop between my house(or my phone) and my bank is a piece of network owned by some company or other. "Use your own network" is meaningless in the context of connecting to any hardware you don't own yourself.
If you provide a publicly accessible "Guest" network isolated from my corporate or private resources, that I agree that it's unreasonable to intercept TLS sessions.
If you are on my network, which exists to serve my constituents with a personal device, I have every right to or even have a duty to ensure that you aren't threatening the overall integrity of the private network. Whether that be exfiltrating data, bringing in malware, etc.
In 2016, the answer to this issue is really simple -- bring your own cellular service.
If someone doesn't want to install the root cert, then "use your own network" is a perfectly fine response.
If someone is upset that the TLS security model is broken in half, then "use your own network" is not a valid response.