The law doesn't clearly state what's illegal. In this case, it barely mumbles and gestures at it. In applying the law, it is inevitable that it will have to be more precisely defined (or, worse, applied inconsistently).
The law isn't particularly confusing. There's just been a multi-decade lobbying effort funded by the most powerful and moneyed interests in the country to muddy the waters about this.
I didn't say "confusing". I said "unclear" and "underspecified". I'm looking I the words of the law myself and I have no idea what should and shouldn't be illegal.