Basically if I google "watch Xyz online" I will get a long list of results where I'm 2 clicks away from watching Xyz - how am I supposed to know which of those are legal sources? For some movies the top result can be youtube. For others it will be watchseries.{whatever tld they use this month}. Unless everyone makes all their agreements and contracts public, I can't reasonably tell if they are allowed to redistribute.
Fraud is about money, and money is issued by the state. As such, fraud is a crime against the state and thus considered as serious by the state.
If we view copyright as an granted monopoly by the state, then declaring it as a felony would follow a historical pattern. As a property hover, it does not.