[mindcrime]

but it would nevertheless be very difficult to obtain such a certificate.

Not if you're the government. Just send the root CA a "National Security Letter" and bob's yer uncle.

[uh_oh]

We were are talking about a random guy in front of the house, not the government.

[mindcrime]

But the set of "random guys" who might appear in front of your house includes potential government agents.

[lmm]

No, they're nonrandom. And more to the point, it's worth defending against some threats even if you can't cover all.