Your wifi and home network probably are closer to 1% than 0%.
at 1-10%, you're probably on some kind of shared connection (CMTS or GPON with TDMA) and your provider has an overloaded network design (and you're at the end of the upgrade/split queue).
at anything above 10% you're in the realm of weird broken stuff. Congestion on the internet between major providers is a thing but is far less common than it was a decade ago, it does still happen though. Major providers who have NECMP or NLAG links inside their backbones or between providers where one of the links breaks in a way which doesn't remove it from the ECMP/LAG and suddenly you drop 1/N of the traffic (where N might be 2 == 50% loss). More common was finding LAG/ECMP where 1/N of the links was oversubscribed but the others were fine due to unequal traffic distribution.
> noisy RF, industrial
Pretty uncommon in my experience as most of these environments are not as cost optimized and know already that they will be in weird RF/electrical environments so they just use wired ethernet (and even shielded cable for really janky situations).
While there are strategies to reduce congestion on backbone links, they are not commonly implemented and even less commonly implemented well and sometimes implemented intentionally poorly.