> If my country would do this - and it is very well possible they do
Probably any country that can devote resources to industrial espionage does it.
> I'd be very much ashamed of this
"Playing nice" puts you at an disadvantage against actors that are more uninhibited. There is a reasonable argument to be made about scale and proportion; eg, the use of overwhelming capabilities in extremely asymmetric situations. But that doesn't negate the utility of those capabilities.
The uncomfortable reality is that all things exist naturally in a state of conflict (or "competition", to put a nicer spin on it). Morality is perhaps the greatest of the human inventions, but being unnatural, it does not exist in a stable equilibrium, and is rather irrelevant (and sometimes damaging) from a survivalist game theoretic perspective. Like capitalism, the rise and fall of nations mirrors Darwinism on a macro scale, so with that in mind, what we're seeing here should not be surprising -- it is the struggle for survival playing out over decades and centuries. The morality of an action, on a national scale, is a secondary concern, although it is often invoked if the effect on the nation is at least neutral or positive.
So that's why the US won't launch an outright attack against French industrial interests -- the consequences would be too damaging, not to mention the moral aspects of War Is a Bad Thing -- but has no compunction about stealing industrial secrets or snooping on politicians, where the potential gains outweigh the risks. And vice versa, for every nation that does this.
The "rules of the game" are dictated only by self-interest. Is it fair? No. Probably the only way to solve that is to collectively attain (and sustain!) enlightenment.
> rest of the world (the people, not necessarily the governments / those in power) considers industrial spying to be a negative activity
That is only true when the people/government are not the beneficiaries of the information. In reality, states (and people) will (and arguably, should) take any advantage that's given to them. Again, the reasonable argument to be made here is one of scale and proportion, not an absolutist directive of This Should Never Be Done Because It's Bad.
> 'They do it too' is such a lame excuse anyway
Yes, "they do it too" is a poor justification for anything, but it's not really the argument here. The argument is that not doing it would be more damaging to national economic interests. (I hate having to say this, but I feel like it needs to be spelled out, especially on the Internet: this is not me agreeing with anything the US is doing here, only giving a rationale. Although I will admit I'm not quite as idealistic in my convictions as you are.)