Fair point. I think the American TLAs know that the very day they are even once caught red-handed with a bogus CA-signed cert, the browser vendors will quickly

Fair point. I think the American TLAs know that the very day they are even once caught red-handed with a bogus CA-signed cert, the browser vendors will quickly start beefing up security with measures like DANE, making any attack on HTTPS even harder. This could also be disastrous to the breached CA's business, if browsers start rejecting it, which in turn could have major political implications - the overall revenue of the American CA companies measures in billions. Surely they would have otherwise already done it, right? They certainly have the capability to compel a CA to do it.