The thing about defense contractors like Boeing and Raytheon is that if they do receive information from the CIA or NSA, they're not gonna talk about it for fear of losing the existing contracts they have, or losing bids in the future.
I would agree that spying on China is harder than say spying on France. But I wouldn't say it's impossible. The US just has to work 10 times as hard. I would also say that because of the regime, any Chinese turncoats would be have much less loose lips.
James Mulvenon, leading expert on PRC cyber who was one of the loudest sirens 10 years ago also basically said there was mutual offensive attacks - something like "We hack them, they hack us". The distinction Americans and Mulvenon like to make back then was PRC civil military fusion = PRC can economically weaponize hacking, i.e. PRC can pass hacked blueprints to companies XYZ to develop vs US can't because NSA can't pick winners. Which is fair (unless it comes to stuff like Airbus vs Boeing or other strategic industries). But that's just sour grapes for admitting that PRC has a better system for industrial espionage.
Anecdotal, in PRC in the mid 90s, had dinner where diasphora Chinese at western telco was complaining about how PRC started hacking their networks, someone else at dinner worked for domestic telco (trying to poach), and used to technician in PLA sigint unit, complained about how US penetrated most of Chinese networks and lamenting how they were w decades behind in cyber.
Like something out of cyberpunk literature. Squat, solid buildings without windows, surrounded by razor wire.
Nobody talks about industrial espionage, but it's constant in nation-state important industries.
In the country I originally come from, it was uncovered that the US was spying on one of its companies. Not China, the US.