Do you have any evidence that AI providers aren't using residential proxies?
It's impossible to prove a negative. They could all be running secondary scrapers using malware proxies... but what we do have is plenty of evidence of them using fixed IP pools with appropriate user agents. I don't see any Chinese user agents... so two guesses who may be driving the bulk of these AI scraper requests via residential proxies.
Those rates are still cheaper than some datacentres charge in parts of the world.
If I hear the fan spinning at night, you're probably getting caught immediately.
If you pop my mom's TV box and use it to route data within the connection's capabilities, you're getting away with it. If you consume a little bit of resources, still. If you consume enough to be useful for these kind of challenges, chances are her TV playback will start to stutter, which will be resolved by taking the compromised TV box, and removing the malware using advanced mechanical means called "a trash compactor".
video decoding is hardware accelerated, and there's probably enough excess compute to be able to do some sort of PoW challenge. Besides, unlike humans, bots aren't in a hurry, so they can spread out the work across a long time to minimize disruption.